Been searching for a thread on here from J15 builders identifying clutch m/c size but cannot find it. I took a note previously and I think the answer was 0.7 in. Can someone please confirm. TIA.

I have a 0.75" on a std Ford Sigma concentric slave cylinder.

Thanks for that, I will try not to loose the note this time. To avoid doubt I will order at once!

Agree with the use of the 0.75