Thanks all
The XJ has a bit of an annoying vibe above 80kph, and the brakes pull to the side if you stomp 'em, and our mechanic says, well this and that's a bit worn, but not so much so that he'd say 'yes, that's the culprit', or even 'that's gotta be replaced'.
Everything's going to get overhauled in due course anyway, and we'd like to get it done right!