Thank you to everyone who has pointed me in the right direction, especially Jeff for taking a bolt out of his bike and measuring.
So I calmed down after work this afternoon and washed a caliper bolt then measured it about a dozen times, finally counting 20mm of thread to give me a better chance of accuracy until I counted 16 threads several times confidently to establish that it certainly is 1.25 as it should be.. Sorry to get you guys at it but it was driving me nuts!
So I'm sorted now thanks, with the proper bolts ordered from RSMoto Titanium.
I also got my caliper pinch bolts from them, which are also Ti and the proper low head jobbies too.
https://www.ebay.co.uk/itm/Ducati-74...8AAOSwrIRe~Hbm
So yes Kato, I knew that the banjos and bleed nipples are 1mm pitch so that gave the 1mm pitch caliper bolts credibility in my head.
So if it is the case that the 40mm spacing calipers are 1.5 pitch then my now spare set should fit those, although I believe they are 35mm long and not 25? So if anyone can use them for a tenner posted they are yours.
Still can't really forgive the Ducati workshop manual for telling me they are M10x1.5. It does beg the question; is the torque figure correct for the 1.25 pitch bolts?