Early efforts Business interests at Swindon and Marlborough pressed to promote a north-south connection, and a Swindon, Marlborough, Southampton and New Forest Railway was promoted, soon renamed the Swindon, Marlborough and Andover Railway (SM&AR). With considerable support at Marlborough and from the LSWR, and perhaps surprising support from the Marlborough Railway and the GWR, the '''''' (
36 & 37 Vict. c. cxciv) which authorised the scheme received
royal assent on 21 July 1873, with share capital of £375,000 and borrowing powers of £125,000. The Marlborough Railway was authorised to subscribe up to £25,000 in addition, and improvements to their railway could be carried out. The LSWR was to build the third line over that section, and lease it to the SM&AR. In September 1879 work was resumed by Watson, Smith & Watson "on terms guaranteeing interest payments to shareholders at 5 per cent per annum until the line was open for traffic". That firm's financial strength was considered controversial, and it is not clear how the contractor was to be remunerated, but preference dividends were authorised by an act of Parliament, the '''''' (
43 & 44 Vict. c. xviii), on 29 June 1880. Construction now proceeded more rapidly, and the section from Swindon (SM&AR station, later Swindon Town) to Marlborough (SM&A station) was opened formally on 26 July 1881 and to the public on 27 July 1881. There were intermediate stations at Chiseldon and Ogbourne. An accident occurred on 11 July 1881 under trial running conditions at Chiseldon, when a guard slipped from the footboard of a train and his foot was crushed by the wheel of his train. No terms for access to Swindon GWR station had been set, and the company now negotiated with the GWR; the GWR was hostile, seeing the SM&AR as facilitating a potential north–south penetrating route, and the terms went to arbitration; this awarded considerably reduced charges compared with the GWR's initial demands: £3,900 per annum for the use of Swindon GWR station, plus other charges. A passenger service between the SM&AR and GWR stations at Swindon was started by the SM&AR on 6 February 1882. The SM&AR was therefore refused permission to open until the GWR (effectively the managing company for the B&HER and the Marlborough Railway) improved the arrangements at Savernake, in particular providing interlocking and the signalling system on the branch. This required an enabling act, the '''''' (
45 & 46 Vict. c. cxcv). At this time the southern section of the SM&AR was ready, and the company had engaged and trained staff to work the line, so it started a train service from its Grafton station to Andover, beginning on 1 May 1882 and using a temporary connection at the point of geographical junction near Andover (later to be called
Red Post Junction). Permanent use of such a connection was prohibited, and the third track from there to Andover, for the use of SM&AR trains, came into use on 20 November 1882. Intermediate stations were at Collingbourne, Ludgershall and Weyhill. The GWR was not hastening to make the Marlborough line ready for the intruder, and the financial responsibility for the improvement works went to arbitration; meanwhile the officials of the SM&AR, responsible for two separated sections of railway, had to acquire a horse and trap for managerial visits to their line. The works were finalised on 30 January 1883, so finally the SM&AR was able to operate throughout from Swindon to Andover, from 5 February 1883. Its own route ran from Rushey Platt (near Swindon) to Marlborough Junction () and Wolfhall Junction (east of Savernake on the B&HER) to Red Post Junction (west of Andover, ). All was
single track except the connecting curve at Rushey Platt and a short section at Marlborough. The capital expenditure had been over £600,000. ==Swindon and Cheltenham Extension Railway==