Following the adoptions of the flat-topped Belpaire firebox design the GWR revised it's saddle tank engines to eliminate the tank over the firebox, producing a full-length pannier tank design to provide adequate water capacity. Many of the hundreds of saddle tank engines the GWR owned were converted to pannier tanks, but by mid-1920s many of these engines were reaching the end of their working lives and new locomotives were going to be required. Under Chief Mechanical Engineer C B Collett the existing Dean 2721 class design from the late 1890s was fully updated, though some older details remained including the traditional cab style showing it's original open back roof with separate with rear spectacle plate added.
300 of these 57xx class engines were built between 1929 and 1931, mostly by private locomotive builders North British (100) W G Bagnall Ltd (50) Kerr, Stuart & Co (25) Armstrong Whitworth (25) Beyer Peacock (25) and Yorkshire Engine Co (25). Swindon had contributed just 50 locomotives to the total. There was a brief hiatus in construction, but from the next order all remaining 57xx panniers were to be built at Swindon and to a far more modern looking design.
From 8750 onwards a number of changes were made giving the locomotives a much more modern appearance. Most noticeably the roof and separate back sheet look was replaced by the more rounded and integrated 'Collett' cab styling which appeared on the smaller 54xx and 64xx panniers in 1932. Construction of these '8750' panniers re-started in 1933 with a small block of specials, the 9701-9710, a block of 10 locomotives with side tanks and condensing gear for use on the Metropolitan Widened Lines serving a number of goods depots in central London, principally the Smithfield meat market. Standard pannier tanks resumes with lot 282 for 8750-98 and 8700. Actually 8700(2nd), the first Beyer Peacock built 8700 had been converted as a prototype for the condensing tanks 9701-9710 and was rebuilt to match the 10 new build engines and now numbered 9700. A new 8700 was built using the replaced tank and cab sections of 8700(1st), so resembled a 57xx (and was also notable for returning to Swindon after withdraw still displaying the 1934 shirtbutton monogram!). As the 50th set of parts for lot 282 was now 8700 another lot number was issued, lot 285 for one single locomotive, 8799!
Construction of the '8750' type 57xx panniers continued through numbers 9711-9799 (1934-1936), 3700-3799 (1936-1938), 3600-3699 (1938-1941), 4600-4699 (1941-1945), 9600-9661 (1945-7946), to the last GWR batch, 'shunting only' locos 6750-6759 (1947). GWR lot numbers and construction continued after nationalisation with 9662-9672 (1948) more of the 'shunting only 67xx type, 6760-6769 which were the first fitted with BR smokebox number plates, 9673-9682 (1949) and a final 10 'shunting only' locos 6770-6779 in 1950.
From the fleet of 863 57xx panniers several were sold for further use by London Transport and the NCB. From these and those locomotives lucky enough to be purchased for scrap by Woodhams of Barry 16 have been preserved, still proving to be highly capable and efficient locomotives.
Features of the Dapol O gauge 57XX & 8750 models
- Die cast Chassis and footplate for excellent adhesion and pulling power
- Powerful 5 pole motor providing fine power control
- Beautifully detailed body with correct body type variations applied where relevant with many separately added details
- Partial representation of working inside motion and many other exquisite fine details
- • Four cabs for original 57XX, Later 57XX, 8750 Collett cab and London Transport cab
- Sprung Buffers
- Removable roof, secured with magnets for ease of fitting engine crew
- Working cab doors, where fitted
- Flickering fire box glow
- Ash pan with correct double brake rodding
- Expertly applied livery
- Wheels conform to the new O Gauge standard, suitable for O Super Fine
- DCC Ready with a 21 pin decoder socket
- Sound fitted versions offered, Sound recorded from L92 (5786)