UNLESS...it's the "Raleigh" English headset!!

Standard English headset threading is 1" x 24 tpi, ...BUT the "Raleigh" English is 1" x 26 tpi.
(tpi=threads per inch)

"Close, but no cigar!" as my Dad used to say.

I'm having East Hill's mixte fork steer tube replaced to accommodate the "standard" English headset.
So we can use a Campy headset.