Murray
Many thanks.
I'll have a good look at the system. A bit of lube and correct adjustment may sort things.
I 'think' the lever is actually stuck, at least that's how it seemed when the MOT mechanic showed it to me. If I back off the cable tension, I should be able to determine whether or not it's actually seized. If so, then a bit of a clean and WD40 will be my friend.