Don't know when - 40's at a guess? Is that an air raid shelter in the background? If so - during WW2 or just after. Names?
From Keith Tyler: Thought to be c1946/7. I don't recall a shelter in that position. The only ones were at the canal side of the field into the bank. I think the shot shows the high wall by the groundsman's 'premises' off the rear playground. The girls would be sitting on the low wall which faced them towards the school field.