Update from vet: still no platelets but that's to be expected at this stage (more bloods to be taken in 2 days) + still unsure what's behind this and not ruling out infection, neoplasias, or something else. Praying for this to have been just one of those things despite it being a serious one of those things.
Wilf is being Wilf and has amused the vet nurses by not peeing in his bed anymore (bearing in mind he's on really high-dose steroids so has an urge to pee a lot) but has managed to pee out of the kennel door on to the floor. Vet said if this is him being quiet as well re his vocalising she'd hate to know him when he's well LOL
Anyone who knows Wilf will know what a big little character he is and has been since he was a pup