Hi Derek, long time no hear, hope you are well etc etc.....
The John L Brown has always been a bit of a funny one. There are a few copies about and yet it commands a reasonable price, I've seen it sell for £200-300. Whether it is legit or not is open to some speculation. I was told once that it was a bootleg (though why such a slow side would be bootlegged is a bit of a mystery, unless for the Jamaicans or something) , and certainly the B side sounds like a "Wigan instrumental" from the mid 70s. Anyway it's a lovely record and one I too have played on occasions. Good luck in solving the mystery...I am sure it is actually Mancha as well by the way Steve