Between 1864 and 1905 fifteen distinct classes and sub classes of 0-6-0 tank engines were built at Swindon and Wolverhampton, providing the Great Western with over 1,100 light goods, shunting and branch passenger engines. The 5700 and later 8750 class pannier tanks can trace their origins back to these saddle tanks from the Armstrong and Dean era.

A good proportion of these earlier saddle tanks were converted to pannier tanks to prevent problems with injectors due to overheating of the water in the saddle tank. The 57XX, although separated from them by 24 years, were an almost unaltered continuation of the saddle to pannier tank conversions of the 27XX with a reversion to the spring arrangement and non-fluted coupling rods of the previous

Their dimensions were:-

5700 Class

By 1929 superheating, had been found of little value on shunting engines, the two 51/8" superheater flues, being incerted in the top corners of the firebox tubeplate to prevent cracking at these points. The 200lb boiler pressure was higher than on the older engines and enclosed cabs with enlarged bunkers were fitted from the start.

Externally the chief feature to distinguish them from the older engines was the universal cast iron chimney. Of the first one hundred engines, fifty were built by the North British Locomotive Co. Ltd., Nos. 5700-24 at the Hyde Park Works and Nos. 5725-49 at Queens Park. Of the Swindon engines Nos. 5780-99, then Nos. 5768 & 70-8 had boilers on which the steam supply to the fountain in the cab was taken from the dome in a covered pipe along the tank top. This feature was discontinued, but the boilers found their way to other engines before it was finally removed.
Nos. 5790-99 were built with Automatic Train Control apparatus and the earlier engines were also equipped in the next few years. Two hundred further engines were built in 1929-31, all by outside firms under a Government scheme to alleviate the effects of the trade depression. These were -Nos. 6700-49, 7700-99 and 8700-49, of which Nos. 6700-49 had steam brakes only and three-link couplings, but as there was little work for this batch most of them were stored for a couple of years. The A.T.C. apparatus was put on Nos. 7750-99, 8700-49 on arrival at Swindon and on Nos. 7700-49 a few years after they were built. Nos. 5700-99, 7700-99 and 8700-49 were fitted up for vacuum brake but Nos. 5700-49 were built without steam heating apparatus although several subsequently acquired it. Nos. 7700-25 / 75-99, 8700-49 arrived with polished brass safety valve covers, most of which were soon painted over, although in later years many of the class had again been brightened by the removal of the paint.

Condensing Engines

For many years engines with condensing apparatus (0-6-OT's of the " 633 " class and 2-4-OT's) had worked over the Metropolitan lines to Smithfield. These older engines were now becoming due for replacement and No 8700 was converted to a condensing engine in March, 1932. The tanks were cut back at the smokebox end, the capacity being reduced to 1,080 gallons, and a vertical feed pump fitted on the right side.

Branch pipes from the smokebox conveyed exhaust steam to the centers of the tanks which were provided with steam vents. The weights (full) became 17 tons 7cwt. + 17tons 7cwt. + 16tons, total 50tons 14cwt.

As a result of experience with this proto-type ten new engines, Nos. 9701-10, were built at Swindon in the following year. On these the tank capacity was increased to 1,230 gallons by forming the rear part of the tanks into side tanks and a much improved form of cab with rounded roof, much larger windows and sliding shutters adopted. Coal capacity was however reduced to 2tons 16cwt. At the same time the boilers supplied had slight modifications (Class PJ). No. 8700 was similarly modified and re numbered 9700 in January, 1934. Nos. 9700-10 had special A.T.C. apparatus which was automatically clipped up clear of the live rail upon entering an electerfied section and released on leaving it. The weight (full) was increased to 50³/₄tons (16tons 16cwt. + 17tons 4cwt..+ 16tons 15cwt).

8750 Class

Subsequent engines starting with No. 8750 were all built with improved cabs, class PJ boilers and A.T.C., with the exception of the second No. 8700 which inherited the cab and number plates of its predecessor. The class was now sub-divided into 5700, 8750 and 9700 condensers groups. To prevent steam from the whistles obscuring cab windows small deflector plates were fitted to guide the steam flow over the cab roofs.

No. 9773 was the first engine to be modified and two years later commencing at No. 3774 or thereabouts, a larger type was introduced. This was standard for the engines with large cabs, the shorter pattern being fitted to the earlier engines. Further improvements were incorporated in No 9795 (9/36) and subsequent engines with pocket steps welded onto the bunker on the firemans (L.H.) side and additional handrails to facilitate access to the bunker. Engines built prior to these modifications were gradually brought into line as they passed through the shops. The weight was increased to 49tons, 17tons - 17tons - 15tons.
In 1942 a new type of top feed appeared, with separate clackboxes housed in a much taller cover than the Churchward pattern, and internal delivery pipes in place of trays. The point of delivery was very carefully chosen to prevent trouble from local cooling. No. 8770 and 5735 were the first of the older engines to be modified, and No. 4656 (5/43) the first to be built as new, although it did not seem to have become standard for new construction until 1944. From then top feed apparatus had been put on many of the older boilers and some engines built with it, had lost it due to boiler interchange. Nos. 6750-79, like Nos. 6700-49, had steam brake fittings only.
During the Second World War the " 5700 " class began to be used at Didcot Ordinance Depot and spark arresting chimneys were fitted to Nos. 3709/21, 4601, 5710/44/52, 7709, 8738/57 and 9722 while No. 7709 also had the 'bird-cage' type. Nos. 5757 and 7713 had however acquired spark arresting chimneys by 1938 and 1937 respectively.
In -May, 1946, No. 7722 was fitted with winding gear for working the Pwllyrhebog incline on the Taff Vale line, also one or two engines had the upper lamp iron moved to the smokebox door.

Allocation and Work

So far as axle loadings would permit, the class was distributed throughout the system and only a few sheds did not have them. In 1950 it was decided to allow the class (except -Nos. 9700-10) to run over "Yellow" routes due to their negligible hammer-blow so that by February 1954, only Truro, Abercynon, Treherbert, Aberystwyth and Machynlleth had no allocation.

The distribution by Districts in February 1954, was London, 121; Bristol, 112; Newton Abbot, 61; Wolverhampton, 125; Worcester, 33; Newport, 178; Neath, 139; Cardiff Valleys, 83; Central Wales, 6. The other five were at Birkenhead, having been classed as London Midland Region stock with effect from 19th April, 1953.

The 67XX were not as widely spread as the rest of the class. as they were purely shunting engines with steam brake only. In 1954 they were shedded as follows; Swindon, 4; Newport Pill, 20; East Dock, 1; Swansea Paxton Street, 2; Cardiff East Dock, 21; Barry, 19.

Returning to the engines fitted with vacuum brake ejectors, not only were they used for shunting and local freight working but were used quite extensively in most areas for branch and short-distance main line passenger trains. With comparatively light loads they often made some very lively running and were occasionly used as standby engines for those of larger classes, and their efforts to keep time with heavy loads were often accompanied by firework displays!

Under British Rail they were Power Class 4F and the standard livery was unlined black, although there were exceptions that were lined, and many had the safety valve covers polished. Nos 6760-79, 9673-82 were built with smokebox number plates and all but Nos. 3656 and 3742 of the earlier engines were fitted later. It would seem that all Swindon built locos had cast iron cabside numberplates but the specification for contractor built numberplates was usually brass.

No. 7711 was transfered to the London Transport Executive in October, 1956, and becoming L.T. No. L90 was repainted in lined maroon livery (the first of several).

Withdrawals

Build Dates

Nos.	Builder	Lot	Built
5700-49	North British Locomotive Co. Nos. 23818-67	256	1929
5750-79	Swindon	258	1929
5780-99	Swindon	260	1929-30
6700-24	W. G. Bagnall -Nos. 2381-2405	262	1930
7700-24	Kerr Stuart Nos. 4435-59	263	1930
7725-49	North British Locomotive Co. Nos. 23921-45	264	1929-30
6725-49	Yorkshire Engine Co. Nos. 2249-73	265	1930-1
7775-99	Armstrong Whitworth Nos. 1131-55	271	1930-1
8725-49	W. G. Bagnall Nos. 2422-46	272	1930-1
8700-24	Beyer Peacock Nos. 6680-6704	273	1931
7750-74	North British Locomotive Co. Nos. 24038-62	274	1930-1
9701-10	Swindon	282	1933
8750-98 8700	Swindon	282	1933-4
8799 9711-59	Swindon	285	1934-5
9760-84	Swindon	293	1935-6
9785-99, 3700-34	Swindon	299	1936-7
3735-84	Swindon	306	1937-8
3785-99 3600-34	Swindon	314	1938-9
3635-84	Swindon	325	1939-40
3685-99 4600-34	Swindon	330	1940-2
4635-60	Swindon	336	1942-3
4661-99 9600-21	Swindon	352	1943-5
9622-41	Swindon	355	1945-6
9642-51	Swindon	356	1946
9652-61 6750-9	Swindon	362	1946-7
9662-72	Swindon	370	1948
6760-9	Swindon	374	1948-9
9673-82	Swindon	378	1949
6770-9	Swindon	379	1950

Preserved

3650	Didcot Railway Centre
3738	Didcot Railway Centre
4612	Bodmin & Wenford Rly
GWR no. 5764, LT no. L93	Severn Valley Railway
GWR no. 5775, LT no. L89	Keighley & Worth Vly Rly
GWR no. 5786, LT no. L92	South Devon Railway
7714	Severn Valley Railway
GWR no. 7715, LT no. L99	Bucks Railway Centre
GWR no. 7752, LT no. L94	Birmingham Rly Museum
7754	Llangollen Railway
GWR no. 7760, LT no. L90	Birmingham Rly Museum
9600	Birmingham Rly Museum
9629	Pontypl & Blaenavon Rly
9642	Dean Forest Rly
9681	Dean Forest Railway
9682	North Norfolk Rly