The Novice - thanks for the reply. However I thought that measurement applies to the distance between the back plate and the spur, not the spur length? (I'm happy to be corrected as I'm totally new to this)
Any idea where I might be able to get replacements for these window fittings? I've been Googling for days but all the spurs on the cockspur handles I've found are 28mm, whereas these are 20mm. I'm not even sure they class as cockspur to be honest. In fact, the only similar ones I've found are...