The remaining 17 complete kits at Woolwich were bought by the Southern Railway .
The remaining 17 complete kits at Woolwich were formed the basis of later locomotive classes such as the three - cylinder SR W class 2 - 6 - 4 tank locomotive .
The remaining 17 complete kits at Woolwich were bought by the Southern Railway , and formed the basis of later locomotive classes such as the three - cylinder SR W class 2 - 6 - 4 tank locomotive .