When this question came up in Macclesfield Quiz League, in October 2017, I was pretty sure that the answer was 8 feet 6 inches – and so, I think, were several other people in the same room at the time.
Wikipedia confirms however that the answer given was correct, adding: "The regulations came about due to the United Kingdom and the rest of the world playing at different lengths and 7 ft 9¼in (2.37 m) was the compromised length."
© Haydn Thompson 2017