In order to better provide artillery support in the highly mobile desert warfare of the
North African Campaign, the British Army had quickly adapted the
Valentine tank into a self-propelled 25-pounder gun: the
Bishop. Introduced in 1942, the Bishop proved to have many problems in service. In particular, limited space meant that the turret had little elevation, requiring crews to use natural slopes, embankments or mounds to get the full range out of the gun. As a stop-gap, the US-built
M7 Priest, with an
M101 105 mm howitzer, mounted on an
M3 Lee chassis, was soon replacing the Bishop, reaching service in October 1942. In March 1942, the UK ordered 2,500 for 1942 with another 3,000 for 1943. The first M7s were rushed to Egypt for the
Second Battle of El Alamein, where they played an important part. However, because the US 105 mm gun was not otherwise used by the British military, supplying ammunition to Priest crews was complicated and caused delays. Simultaneously, two new self-propelled 25-pounder projects were being pursued by the British General Staff. Firstly, in the US, the 25-pounder Howitzer Motor Carriage T51 – a Priest adapted to mount the 25-pounder – was tested from July 1942. Development was delayed by issues including the destruction of the gun mount on the prototype, during the first live-firing trials. where it underwent further trials. In May 1943, it was formally accepted for use by the British Army and given the name "Sexton" (after the
religious custodian and following in the tradition of the Bishop and the
Deacon self-propelled guns). A UK order for 300 Sextons was made in mid-1943, albeit built on the hull of the
Grizzly tank (a Canadian-built variant of the M4A1 Sherman). The Ram-based SP gun became known as the Sexton Mark I, while the Grizzly-based variant was the Sexton Mark II. UK orders for the Sexton II eventually totalled 2,026 vehicles. The Sexton was generally regarded as a successful project, unlike the Ram (which never saw combat in its original form). Between 1943 and 1945, the
Montreal Locomotive Works manufactured 2,150 Sextons for the use of both Canadian and British forces. The vehicle entered service in September 1943. In spite of its confused origins, the Sexton was a combination of proven parts and proved to be a successful design that remained in British service until 1956. ==Operational service==