I only dismantled the front brakes for cleaning (along with various other bits), leaving the rears in situ.
So as I’d used all of the Cider Vinegar on the parts cleaned thus far, I tried my luck in the town centre whilst at work to see if I could find any more, to do the back brakes.
Couldn’t find any cider vinegar, but did find some white wine vinegar.. so I’ll be trying that tomorrow.