Update: new discs, pads, and stainless hoses fitted at the front (rears done previously). I have a pre-owned master cylinder and servo on hand so that'll be the next step if this issue rears its' head again.
I also fitted the servo brace bracket kit from MG-Mania - that's a seperate tale for which I'll start a new post. In brief, the bracket as supplied does not fit correctly and had to be adjusted to make it work.