...unless you're planning to move down to the Med I wouldn't get too hung upon it.
On average, we have about 30 'hot' days per year in the UK.....the other 335 days are usually cool, cold or absolutelyfucking freezing...
Strangely enough, my trusty old textile Wolf jacket was getting a little tatty, so I thought I'd traet myself to another, however the new Wolf stuff is just total crap...so I too went the leather route...bought myself a plain breathable black jacket and matching keks...I used 'em in the French alps in June...it was fooking hot...they were brilliant...
I wore some of those long johns under, that wicks away the sweat...but keeps you toasty on the cooler days...