The TFM class is a subgroup of the _T__ ice van group.
There were two types: 12 ton vans and 15 ton vans. These vans were insulated and were not fitted with ice troughs. The letters "FM" probably stand for "Fresh Meat" or "For Meat". The former description is believed to be more applicable.
The 12 ton vans were short wheelbase type numbered 121 - 130, 134, 141, 142, 144 - 146, 148 - 155, 157, 159 - 167, 169, 170, 172 - 177, 179 - 181, 184 - 191. These numbers are from a 1929 booklet and it appears the number block may have been 121 - 191. The missing vans may have been converted back to T vans with ice troughs by this date.
The 15 ton vans were long wheelbase types with three axles/six wheels at the time. The numbers for these vans were 369 - 392 inclusive.
The writer has no dates for the demise of the class. However it appears that when the six wheel conversions to autocoupler/four wheels was underway, the vehicle were modified back to standard T vans.