Since moving house I’ve been trying to find a replacement handle for our PVC front door. It appears that most handles are of one standard fitting, but there are a couple of different variations of which mine is one of them.
Measuring the distance between the centre of the handle and the centre of the circular part of the lock gives the information needed to check what size of handle is required. The most common is 92mm, where as mine was only 70mm (there are other variations at 68mm and 72mm, which I believe are even less common).
None of the standard DIY / hardware shops that I tried sold these, until I found Morris Mica hardware and locksmiths in Headless Cross, Redditch.
The staff were very helpful and after some searching found only white handles in the store which would fit, but did have a Hoppe catalogue with details of others available. For a £5 deposit they ordered me a new handle, which arrived in stock the following day.
If you need that elusive hard to find door handle then give: Morris Mica Hardware a try.