if you're replacing the cleats "like for like" and they're in the correct position, just draw round the old ones in-situ with a fine-line marker, remove and replace. As far as the knee-ache... I think entire medical treatises have been written on this subject. My right knee is really dodgy (it's been strapped together with kinesio-tape in one form or another since july last year, when I had a small operation on it...) but I ended up with the specialised BG footbeds and the little wedges that go underneath the footbed to "cant" your foot to one side - this straightened up my knee - the left one tracked straight/parallel to the top tube, but the right one "threw out" away from the t/tube at the top of the pedal stroke. The wedged straightened things up a little, and the kinesio tape held it in place until the muscles "tightened" and held me in place again.

To be honest, if your knee was okay up until recently, it could just be that the cleat was already wearing before ripping it to bits on rosedale. You say it's the left foot - is that the one you unclip to stop at traffic lights etc ?? Because it's surprising how little wear and tear on the tip of the cleat is needed to throw things slightly out of whack...

I'd swap to new cleats, in the same position as old ones, ride for a bit, and see if there's any improvement. Then possibly, if it's still needed, experiment on the turbo for a session - trying to alter the angle of the foot ever so slightly heel in/out and see if there's any change / improvement.

I use the (Yellow) SPD-SL cleats with a 6° float (movement) built into them.

Are your cleats fixed or do they have some degree of 'float' built into them?

if you're replacing the cleats "like for like" and they're in the correct position, just draw round the old ones in-situ with a fine-line marker, remove and replace. As far as the knee-ache... I think entire medical treatises have been written on this subject. My right knee is really dodgy (it's been strapped together with kinesio-tape in one form or another since july last year, when I had a small operation on it...) but I ended up with the specialised BG footbeds and the little wedges that go underneath the footbed to "cant" your foot to one side - this straightened up my knee - the left one tracked straight/parallel to the top tube, but the right one "threw out" away from the t/tube at the top of the pedal stroke. The wedged straightened things up a little, and the kinesio tape held it in place until the muscles "tightened" and held me in place again.

To be honest, if your knee was okay up until recently, it could just be that the cleat was already wearing before ripping it to bits on rosedale. You say it's the left foot - is that the one you unclip to stop at traffic lights etc ?? Because it's surprising how little wear and tear on the tip of the cleat is needed to throw things slightly out of whack...

I'd swap to new cleats, in the same position as old ones, ride for a bit, and see if there's any improvement. Then possibly, if it's still needed, experiment on the turbo for a session - trying to alter the angle of the foot ever so slightly heel in/out and see if there's any change / improvement.

I also use the BG footbeds and have a shim in my left shoe for my knee

Excellent - to be honest, there's really no substitute for just tweaking and perfecting. That's why when you DO get it sorted, it's such a wrench to either swap pedal systems or worse still - have to buy new shoes! I was mortified a couple of months ago, when I swapped my cleat, I managed to strip one of the threaded inserts in the sole. Couldn't chase up replacements anywhere (Specialized being a bit of a pain as to who they'll let have stock to sell mail-order in the UK) and ended up getting the metalworking tools out and cutting my own replacement one out of a old Shimano SPD plate. Bit of dremmeling, and a quick file down and it's probably better (read more robust) than the original. Was soooo relieved. Really didn't want to have to throw a perfectly serviceable £120 pair of carbon soled shoes for the sake of one tiny bit of metal! Especially as, if I had, I know that i'd only have replaced them with something that I COULD get spares for. Which, given the shape of my feet, would have probably meant a pair of Sidi Mega's...

Just a thought...have you increased climbing, intensity a lot as the weather become nicer? That's the frequent cause of my knee pain, just doing too much, too soon.

I'd put good money on that being the main reason as well, tbh... going from riding on your local (relatively flat) roads to climbing things like rosedale chimney and some of those climbs up north of harrogate... All it takes is the quads to over-tighten a little to alter the "micro-tracking" of your knee and it'll feel sore very easily!