In article ,
(1577+2260) wrote:

The South West Trains and South Central inner suburban trains: Class
455. These are similar to 315 but run on 3rd rail and are a bit newer.

In fact, apart from the ex-class 508 trailers in some class 455 units the
455s are rather different from the 313 etc classes. 317s & 455s have mark
3 style steel bodies whereas classes 313/4/5/6/507/8 have aluminium bodies
like the PEPs which were their prototypes.

--
Colin Rosenstiel