K1 The first standard public telephone kiosk introduced by the United Kingdom
Post Office was produced in concrete in 1921 and was designated K1 (Kiosk No.1). The Post Office had taken over almost all of the country's telephone network in 1912. Some local authorities refused to give permission for the K1;
Eastbourne Corporation insisted that the kiosks could only be installed if they had thatched roofs. The design of the K1 was not of the same family as the familiar red telephone boxes. As of 2021, there remain fourteen K1 boxes in the UK, including seven that are in museums and museum collections. A further two remain in the Republic of Ireland. Seven of the UK's fourteen have been
listed at Grade II by
Historic England, some of them still located on British streets, including one situated in
Trinity Market in
Kingston-upon-Hull, and another in
Bembridge High Street,
Isle of Wight.
K2 (home of the
Royal Academy of Arts) in London The red telephone box was the result of a competition in 1924 to design a kiosk that would be acceptable to the London Metropolitan Boroughs which had hitherto resisted the Post Office's effort to erect K1 kiosks on their streets. The
Royal Fine Art Commission was instrumental in the choice of the British standard kiosk. Because of widespread dissatisfaction with the GPO's design, the Metropolitan Boroughs Joint Standing Committee organised a competition for a superior one in 1923, but the results were disappointing.
The Birmingham Civic Society then produced a design of its own—in reinforced concrete—but it was informed by the Director of Telephones that the design produced by the Office of the Engineer-in-Chief was preferred; as the ''
Architects' Journal'' commented, "no one with any knowledge of design could feel anything but indignation with the pattern that seems to satisfy the official mind".
The Birmingham Civic Society did not give up and, with additional pressure from the
Royal Institute of British Architects, the
Town Planning Institute and the
Royal Academy, the
Postmaster General was forced to think again; and the result was that the RFAC organised a limited competition. 's family mausoleum in
St Pancras Old Churchyard, London, may have been an inspiration for the K2's design. The organisers invited entries from three respected architects and, along with the designs from the Post Office and from
The Birmingham Civic Society, the Fine Arts Commission judged the competition and selected the design submitted by Sir
Giles Gilbert Scott. The invitation had come at the time when Scott had been made a trustee of
Sir John Soane's Museum: his design for the competition was in the classical style, but topped with a dome reminiscent of those designed by
Soane for his own family
mausoleum in
St Pancras Old Churchyard, and for the mausoleum for Sir
Francis Bourgeois at
Dulwich Picture Gallery, both in London. However,
Gavin Stamp thinks it "unlikely" that Scott was directly inspired by either of these precedents, arguing instead that "a dome above segmental curves is, in fact, a logical solution to the geometrical problem of designing a sculptural termination to a square pillar when a flat top is not suitable". , London The original wooden prototypes of the entries were later put into public service at under-cover sites around London. That of Scott's design is the only one known to survive and is still where it was originally placed, in the left entrance arch to the
Royal Academy at
Burlington House. In 2019, it was
listed to Grade II* in "recognition of its iconic design status". The Post Office chose to make Scott's winning design in
cast iron (Scott had suggested
mild steel) and to paint it red (Scott had suggested silver, with a "greeny-blue" interior) and, with other minor changes of detail, it was brought into service as the Kiosk No.2 or K2. From 1926 K2 was deployed in and around London and the K1 continued to be erected elsewhere.
K3 The K3, introduced in 1929, again by Giles Gilbert Scott, was similar to the K2 but was constructed from
reinforced concrete and intended for nationwide use. Cheaper than the K2, it was still significantly more costly than the K1 and so that remained the choice for low-revenue sites. The standard colour scheme for both the K1 and the K3 was a light stone colour, with red glazing bars. A rare surviving K3 kiosk can be seen beside the Penguin Beach exhibit at ZSL
London Zoo, where it has been protected from the weather by the projecting eaves and restored to its original colour scheme. There is another in use at
Rhynd in Perthshire. – the vertical panels either side of the letter-slot originally housed stamp vending machines
K4 The K4 (designed by the Post Office Engineering Department in 1927) incorporated a post box and machines for buying postage stamps on the exterior. Only a single batch of 50 K4 kiosks were built. Some contemporary reports said the noise of the stamp-machines in operation disturbed phone-users, and the rolls of stamps in the machines became damp and stuck together in wet weather. This has been widely repeated (including by Stamp) but Johannessen chose not to, having found no evidence to support the story. Ten survive with four in public use at
Frodsham,
Warrington,
Whitley Bay and near
Tunstall, East Riding of Yorkshire. A fine example of a K4 may also be found outside the station building at
Bewdley on the
Severn Valley Railway. There is a fully restored K4 (including correct telephone and coin operations) at the
Bury Transport Museum,
Greater Manchester.
K5 The K5 was a metal-faced plywood construction introduced in 1934 and designed to be assembled and dismantled and used at exhibitions. It is not known how many were produced, and there is little evidence they ever reached more than prototype stage. A replica (constructed using the original drawings) can be seen at the
Avoncroft Museum (
Bromsgrove, Worcestershire), as part of its National Telephone Kiosk Collection.
K6 , London In 1935 the K6 was designed to commemorate the
Silver Jubilee of George V. It was consequently sometimes known as the "Jubilee" kiosk. It went into production in 1936. The K6 was the first red telephone kiosk to be extensively used outside London, and many thousands were deployed in virtually every town and city, replacing most of the existing kiosks and establishing thousands of new sites. In 1935 there had been 19,000 public telephones in the UK: by 1940, thanks to the K6, there were 35,000. The design was again by Scott, and was essentially a smaller and more streamlined version of the K2, intended to be produced at a considerably cheaper cost, and to occupy less pavement space. The principal differences between the two designs were: • Size. The K6 was tall and weighed 13.5
cwt (0.69
tonnes). This compared with and 1.25
tons (1.27
tonnes) for the K2. • Elements of the design were simplified and streamlined, in keeping with the "
moderne" aesthetics of the 1930s. The Grecian
fluting was removed from the door and window surrounds, and the previously separate
pediment and
frieze were merged. • The Crown motif (see
below), which had previously been pierced through the ironwork to give ventilation, was now embossed in
bas-relief. A new, separate ventilation slot was provided. • A new
glazing pattern was introduced. The door and two glazed sides of the K2 each had 18 equal-sized panes of glass arranged in 6 rows of 3. In the K6 the number of rows was increased to 8, and the central column of panes was made considerably wider than those to either side. This improved visibility, and gave a more horizontal appearance to the windows, again in keeping with "moderne" principles. The K6 has since become a British icon, but it was not universally loved at the start. The red colour caused particular local difficulties and there were many requests for less visible colours. The Post Office was forced into allowing a less strident grey with red glazing bars scheme for areas of natural and architectural beauty. Ironically, some of these areas that have preserved their telephone boxes have now painted them red. The paint colour used most widely today is known as "currant red" and is defined by a British Standard, BS381C-Red539.
Kiosk installation: the early years With continued demand for K6 kiosks, siting them was more widespread than ever before. A purpose built kiosk trailer was designed from 1953 to reduce the running costs of cranes.
Numbers installed The K6 was the most abundant kiosk in the UK and its growth, from 1935, can be seen from the BT archives:
Manufacture The K1 and the later K3 concrete kiosks were produced at various (and largely unrecorded) locations, around the country. This made quality control and supervision of the manufacturing process difficult, when compared to the GPO's experience with cast-iron
post boxes, and was an important aspect of the GPO's move towards cast-iron telephone kiosks. Over the years, five foundries were involved in this work for the Post Office. Lion Foundry in
Kirkintilloch, MacFarlane (Saracen Foundry), and
Carron Ironworks near Falkirk all produced batches of the K2, the K6 and the K8. Carron produced the single batch of K4 kiosks. The other two manufacturers were McDowall Steven and Bratt Colbran, both of which produced only relatively small batches of the pre-war Mk1 K6. Many kiosks have been fitted with replacement backs; unmodified examples usually have the identity of their manufacturer marked on a plate on the outside at the bottom of their back panel. The only exceptions are the few Mk1 models made by Bratt Colbran, which are anonymous. A supplementary way of identifying the manufacturer is by means of casting marks on the various component parts – i.e. LF, CC, MF, MS and BC – which were used to various extents over the years. A more consistent manufacturer mark can be found at about shoulder height on the inner face of the back panel. These marks generally identify both the manufacturer and the precise model of kiosk. Up to around 1949, the year of manufacture is also included. The non-BT K6 kiosks erected later, usually painted black, are for the most part new castings from new manufacturers.
Crown From 1926 onwards, the fascias of Post Office kiosks were emblazoned with a prominent crown, representing the British Government, of which the Post Office was an agency. The design was initially the
Tudor Crown, then in widespread use in government service. The same crown was used in all parts of the United Kingdom and
British Empire. On the K2, the design was pierced through the ironwork, and acted as a ventilation hole. On the K6, a separate ventilation slot was provided, and the crown was embossed in
bas-relief. In 1953 the new Queen,
Elizabeth II, decided to replace the Tudor Crown in all contexts with a representation of the actual crown used for most English, and later British, coronations,
St Edward's Crown; it began to appear on the fascias of K6 kiosks. To accommodate the two different designs of crown on K6 kiosks, the fascia sections were cast with a slot in them, into which a plate bearing the appropriate crown was inserted before the roof section was fitted. The crowns were originally painted the same red as the rest of the box. However, since the early 1990s, when the heritage value of red kiosks began to be widely recognised, British Telecom picked out the crowns (on both K2s and K6s) in gold paint. Kiosks installed in
Kingston upon Hull were not fitted with a crown, as those kiosks were installed by the Hull Corporation (later
Hull City Council, then
Kingston Communications). All boxes in Hull were also painted in cream.
Modernisation – K7, K8 and "Croydon" , installed as part of the London Underground's internal telephone system In 1959, architect Neville Conder was commissioned to design a new box. The K7 design went no further than the prototype stage. K8, introduced in 1968, was designed by
Bruce Martin. It was used primarily for new sites; around 11,000 were installed, replacing earlier models only when they needed relocating or had been damaged beyond repair. The K8 retained a red colour scheme, but it was a different shade of red: a slightly brighter "Poppy Red", which went on to become the standard colour across all kiosks. The K8 featured a single large glass panel on two sides and the door. While improving visibility and illumination inside the box, these were vulnerable to damage. There were two versions, the Mk1 and the Mk2, differing mainly in the detail of the roof and the surround of the 'TELEPHONE' opals. The Croydon boxes, painted bright yellow with a black handset silhouette, were erected as an experimental prototype to replace the red telephone boxes. However, although the trials were successful, the quality of the materials and design made it too expensive for the Post Office to mass-produce, and the design was not adopted.
Privatisation and the KX series was privatised by the British government in 1984, existing telephone boxes retained their distinctive red colour (K6 pictured in Cambridge, England in 2007), and around 2,000 of them were given
listed status. In 1980, in preparation for
privatisation, Post Office Telephones was
rebranded as
British Telecom (BT). In February 1981, the
Daily Telegraph mistakenly announced that all the red telephone boxes would be repainted yellow, which was BT's new corporate colour. Despite the fact only 80 or so kiosks in the North West, and 4 in London had been painted yellow as a trial, there was an immediate public outcry; the
Daily Mail launched a campaign "against the yellow peril" and questions were asked in
Parliament. In the
House of Lords, the
Earl of Gowrie, the Minister of State for Employment, called on BT "to abandon this ridiculous scheme". In the
House of Commons,
Mark Lennox-Boyd MP asked
Prime Minister Margaret Thatcher if she would treat the decision "with the greatest possible dismay". Thatcher, who was responsible for the privatisation, would only say that she could "see my honourable Friend's point". Shortly afterwards, BT announced that only 90 of the 77,000 remaining traditional boxes had been painted different colours "as an experiment" and that no final decision had been reached. British Telecom introduced the KX100, a more
utilitarian design, which began to replace most of the existing boxes. The KX100 was one of a series of designs, including the wheelchair-accessible open-sided KX200, and the triangular-footprint KX300. In January 1985, Nick Kane, the Director of Marketing for BT Local Communications Services announced that the old red telephone boxes would be replaced because they "...no longer meet the needs of our customers. Few people like to use them. They are expensive and difficult to clean and maintain and cannot be used by handicapped people". This time, BT did not relent, despite another vociferous campaign. Many local authorities used legislation designed to protect buildings of architectural or historic importance to keep old telephone boxes in prominent locations and around 2,000 of them were given
listed status. Several thousand others were left on low-revenue mostly rural sites, but many thousands of recovered K2 and K6 boxes were sold off. Some kiosks have been converted to be used as shower cubicles in private homes. In
Kingston upon Thames a number of old K6 boxes were used to form a work of art resembling a row of fallen
dominoes. In January 2020 it was estimated that 8,000 traditional red telephone boxes remained in public service. The
KX+, better known as the KX100 PLUS, introduced in 1996 had a domed roof reminiscent of the familiar K2 and K6. Subsequent designs departed significantly from the old-style red boxes. BT followed the KX series with the Multi.phone in 1999 and the
ST6 in 2007.
InLinkUK BT is one of the partners in InLinkUK, a communications service intended to replace over 1,000 payphones in major UK cities. The InLink stations, renamed "Street Hubs" by BT after InLinkUK Ltd failed, provide free public Wi-Fi, phone calls and device charging. == Later use ==