[Lynn Eades]

I just re read your thread.
T58482 was one of batch of 360 3" mortar carriers, contract no.t2035. the serial number range was T58225 to T58584. yours being the 257th built, the builders being Sentinel Wagon.
This info is from page 290 of Nigel's book.
I enclose two mortar carrier plates. The first (Wolseley)belongs to a forum member from the deep south, and the second (Sentinel Wagon) is mine ( sadly,I own the plate only)