Hi all
If you change the pads and find the replacements don't seem to fit terribly well, as well as obvious issues around the pad being too big for the caliper it's also worth looking at the silver coloured plates in each corner of the caliper that the pad sits on.
I noticed one of my new pads (bought in an emergency as they were very worn) was tight to get in to the caliper. The silver plate wasn't sitting totally flush on that side and we suspected a pad material build up underneath, as it was worse where a new pad will sit than a worn one.
Only way to remove the disc to access the caliper properly is to remove the caliper - x2 10mm hex bolts done up to 110Nm that clearly were older than the discs fitted in 2009. One undid, the other rounded. After much swearing and blunting of HSS drill bits, I bought some Cobalt drill bits from Toolstation, along with some cutting lube and it was actually possible to drill out the head of the bolt (to 11.5mm of the 12mm shank) and then give it a tap so the end fell off. Draw the caliper off the stub and hung it from the upper suspension joints with cable ties, and without any torque holding the bolt on you can clamp onto the remains of the bolt and wind it out by hand.
The silver plates are held in with T27 torx screws NOT T25 OR T30!! They have threadlock on them and there isn't much clearance to work. An air line to clear the crud out of the heads helps massively. I used a security key from a Halfords set to get the suspect one out, and found contact corrosion underneath the plate. Cleaned up with a file and gave a light dab of copper grease to act as a barrier and reassembled. Pads now fit properly
New bolts are a couple of quid from TPS to hold the caliper on so no point scrimping on a disc change. I would strongly recommend a decent Snap On or similar hex socket as the Halfords etc quality ones are just not man enough for the job. Luckily one of my neighbours works in a garage and lent me one to make sure the new bolts got torqued properly. As an idea, the Halfords ones are about £5 and Snap On are about £20. One works, the other doesn't.....
At least I know when I do my brake upgrade the newer bolts will come out OK! I wasn't brave enough to remove the caliper bolts on the other side, as the caliper was working fine