394223 at Rugby in April 2001. ©Steve Jones
The MHA ballast/ spoil box wagons were built using redundant HAA underframes by RFS(E) Doncaster in 1997. An initial order for 250 was extended several times until eventually over 1,150 wagons were converted using two distinct body styles. Early examples wore the fish-kind name "Coalfish" and some are still in use today with DB.
(Information provided via Accurascale)