Where were the British horn bands of the 60s and 70s? (If any....)

Yes, totally different.

 
Historically, they emerged in the 19th century as community bands of amateurs, usually associated with specific villages, factories, and mines.

A strong tradition of amateur brass bands still continues today, and there is a National Brass Band Championship, with different ‘leagues’, and about 600 brass bands entering.

Probably the Grimethorpe Colliery Band is the most famous.