If it was the exROD tenders from the Robson 2-8-0s that would be the L.N.W.R. not the L.M.S. If this is the class of tender some of them would be used to up grade some loco classes not forgetting that the L.N.W.R. did also buy some Robson 2-8-0s from the ROD as well, and some would have been used in weedkiller trains, and also for spares.
If it was post WW2 it would most probleby be to provide spares for what I don't know as I've never seen a photo of an ex L.M.S. loco with a ex W.D. Tender.
it is about the Robinson 2 8 0's. I wasn't sure what they were used for.
As for the W.D tender, not so sure. Many years ago a saw a pic of a tender similar to a W.D one coupled to an 8f . However the tender could of been a self weighing type.
The Robinson loco were know as MMs (derived from ministry of munitions) or Military Marys.
In 1919 the L.N.W.R. purchased 30 of the Robinson 2-8-0s from the government (no mention of any spare tenders).
The L.N.W.R. also had 151 of them on loan.
As Crewe tended to work on the engines and tenders in different shops it could be a good idea to have some spare tenders, but 30 seems a lot for a class of 181 locos.