Definitely 1971. Black barathea, as you say - I think that was the type of cloth? Saw the Red Rose badge most often but do remember a few Twisted Wheels. Never really saw football team badges in my neck of the woods. As in London that probably invited too much "close interest", ahem. The Lancashire Rose was more neutral in that sense (until you crossed the Pennines, of course) and as the Lancs CC team was all-conquering in one-day cricket at the time, everyone identified with it even more - at least that's my theory.
I do remember double rear vents. And silver buttons were essential; usually four or five on the sleeve but I can distinctly remember seeing someone with a Twisted Wheel badged blazer with what must have been a dozen buttons on the sleeves right the way to his elbows!
Had PoW check with thin red line myself. Went well with the red socks - and wasn't seen as a matter of football allegiance amongst my mates (or I wouldn't have worn them). Will have to get the light blue variety now though I think.
We all wore red socks, certainly not a statement of football allegiance. Later, other bright colours of socks were briefly worn, but as they looked a bit 'Teddy Boy' they never really caught on.