Sorted - for the time being.
Got the 3 kittens trapped, a boy (tabby and white) and 2 girls (tabby/tortie white and black and white).
The RP (?) and his wife offered to take them on and try to tame/rehome them as they have a dog cage.
Been to the vet came back with the usual flea/worm stuff. Bought them food, litter etc (from the vet!).
The kittens are about 2 months old, in good health if dirty.
Car stinks of pilchards - but it does the deed.
Left trap baited in boiler room as there was an older black kitten snoozing on the pipes so will go back to collect trap tomorrow (and maybe cat).
Derek (Coventry CP) had been trapping there yesterday and picked up 3 cats and 4 kittens - he thinks he may have the mum of these in his lot. Grown up to be done and returned.
The barracks has a long range of heatinhg systems all over the place and the cats get down there and roam.