The Scoop Room in Henley is THE place for ice cream
Went to The Scoop Room (in Henley-On-Thames) the week before the regatta (24th June), after a personal recommendation and wasn't disappointed. The gelato is gorgeous and they give you giant scoops (warning: don't get carried away with the number of scoops, also, it starts melting quickly). I had biscoff on waffle cone. Great and patient service was provided by the beautiful seller. My aunt is very picky and undecisive, so she asked to taste a number of flavours before eventually deciding what to have.
This is just a kiosk on the side of the street. There was no queue on the day we went, however, I expect there will be regular queing in summer months as word gets around, especially on regatta days. Mmm...makes my mouth water, I might drive the 45 minutes to Henley just for this...