All these carriages worked in sets with a corridor composite or corridor brake composite. The two batches had significantly different underframe arrangements. They were in service all over the Southern Region.
Please note that this etch represents the shallow vented (10¼”) version of D2123. A similar deep vented (15″) coach, to the same diagram number, is represented by our product S4S. Carriages 4349-4370 were also to D2123, but had extended side panels for use in Bournemouth 6 coach sets.