SR DRUMMOND M7 LOCOMOTIVE KIT 
A BRIEF HISTORY.
The locomotives which form the subject of this kit were the first design of Dugald Drummond for the LSWR. A total of 105 locomotives were built at Nine Elms and Eastleigh. 
For a detailed history of this numerous class we suggest you refer to the books by the late D.L.Bradley:  
Part two of The Locomotives of the LSWR published by the RCTS 
LSWR Locomotives - The Drummond Classes published by Wild Swan 
Other valuable sources of information and photographs are: 
A Pictorial Record of Southern Locomotives - J.H.Russell - OPC 
Drummond Locomotives - Brian Haresnape & Peter Rowledge - Ian Allan 
Locomotives Illustrated No. 73 - South Western O-4-4Ts - Ian Allan 
Southern Steam Locomotive Survey - The Drummond Classes - Bradford Barton 
The Book of the M7 0-4-4Ts by Peter Swift

VARIATIONS POSSIBLE WITH THE KIT
Frame Length.  The last 50 locomotives were built with a front overhang 15" longer than the earlier locomotives.  

Chimney. The long frame locomotives were fitted with a narrower chimney.  

Reverse. The first 55 locomotives were built with lever reverse the remainder received steam reverse.
 
Splashers and Sandboxes.  The first 45 locomotives were built with the leading sand box combined with the wheel splasher. Drummond then placed the sandbox inside the smokebox with no external filler. These engines had the traditional shape of Drummond smokebox front with wing plates. The next ten engines, the first with the long frame, continued with the smokebox sandboxes which now had an external filler on the smokebox side. The smokebox sandboxes were quickly removed and replaced with boxes beneath the platform, most by mid-1907. When these locomotives required new smokeboxes, from May 1939 onwards, they lost the wing plates.  The remaining engines were built with the original elegant arrangement.

Water Feed. The first 65 locomotives were fitted with conventional injectors. Drummond then built the remaining locomotives with his feed water heating system, the last 20 locomotives having boiler feed from two Duplex pumps. The feed water heaters were inside the side tanks and were supplied with exhaust steam through brass pipes from the smokebox to the front of the tanks. The tanks were clad with false plates which extended forward to cover the extra pipework, giving the appearance of having longer tanks. From 1922 all the cladding was removed revealing the standard length tanks. 

Clackboxes. Numbers 242 to 256 and 667 to 676 were fitted with boiler side clackboxes. The remainder had their clackboxes sited on the bottom of the smokebox tube plate where they were hidden by the splashers. Urie placed the clackboxes on the boiler sides. 

Front steps. The earliest locomotives were built without the footsteps between the coupled wheels. 

Handrail knobs. The earliest locomotives had the forward handrail knob on the boiler some way from the smokebox. On later engines it was mounted further forward. During SR days an extra short handrail knob for the boiler handrail was fitted to the right side of the smokebox. 

Tank Brackets. The SR fitted two brackets to the top of each tank. At the front the bracket tied the tank to the boiler and at the rear the bracket was a lifting eye.
 
Coal Rails. From 1912 two extra coal rails were added. At the same time, bars were fitted over the rear cab windows. Later the coal rails were backed by metal sheeting to stop the loss of small coal. 

Lamp brackets. The locomotives were built with Drummond's socket style brackets. The SR standardised on a design with the socket in the lamp. Many locomotives had the Drummond brackets adapted to accept the standard lamps but gradually the locomotives were fitted with new brackets of standard design. 

Smokeboxes. Some smokeboxes were renewed  with snap head rivets. Many of the locomotives received four clamping dogs to improve the sealing of the smokebox door. 

Handrails on front of tank. During SR days a vertical handrail was fitted to the front of each tank. When the air operated auto-train control system was fitted the right side handrail was moved outwards to give clearance for the operating cylinder. 

Carriage heating pipes. From 1901 onwards the LSWR introduced steam carriage heating. The steam pipe to the bufferbeam ran behind the right side valance. In later years this was lowered slightly and carried by five brackets along the lower edge of the valance. 

Couplings. Photographs show most of the engines in their early years running with a single, long coupling link although some carried three link couplings.  Later the locomotives were equipped with screw couplings together with a hook to carry the coupling when it was not required. 

Brake shoes. Two different patterns are included. 

Cab doors. Cab doors were fitted to the locomotives equipped with the air operated auto gear.

Balance weights. Several different patterns of balance weight were used over the years. The last forty locomotives were built with Drummond's patent balanced crank axles which obviated the need for balance weights on the driving wheels.

VARIATIONS NOT POSSIBLE WITH THE KIT
Conical smokebox doors.  Numbers 242-244 only were built with conical smokebox doors. These were removed during 1904-5. 

Ram pumps. The first twenty locomotives built with feed water heating were equipped with Ram pumps.
 
Auto train gear. 45 locomotives were fitted from 1912 with the South Western cable and pulley gear for working auto trains. It was removed between 1928 and 1936. From 1930 thirty one of the long frame locomotives received the more practical compressed air control system.

Superheating.
In 1921 Urie rebuilt number 126 with a superheated boiler all but identical to that being fitted to the 700 class 0-6-0 locos. This gave the loco an extended smokebox, higher boiler pitch and taller cab. Number 126 was withdrawn in 1937.