If you don't fancy either the cigarette race or polocrosse in the Easter Holidays, and you have no exams to cram for, then you could always try playing soliders, which Riding Magazine suggested in August 1936 as something for the Pony Club to do "when the weather is too hot and ponies too fat to take .. strenuous exercise."
As a child I'd have looked on this and blenched not at all, but as a mother, I'd have gulped a bit at the thought of my darling attempting the tandem driving (the leader was previously trained on foot, but still ... ) I wouldn't have fancied holding the hoop either if it all went wrong.
As for the surfboard, maybe the riders' descendants are now horse surfing.
Alas the author of the piece, Gwen M Parry, doesn't mention which branch of the Pony Club this is. If anyone has any idea please let me know. The branch shown had just got back from Belfast, where they did a display at the Royal Ulster Show.