There's a brief mention in Garrick's biography of a 1969 performance at the Farnham Festival, which seems to be a trial run of 'Mr Smith's Apocalypse' so maybe this is it. Garrick had very strong working links with Hampshire Schools at around this time, which might be the reason this concert was done and the LP pressed. What a find !
Looks like the original owner of this LP must have lived in Charlton, South London.