The 1952 ASA standard tripod screw specification is 1/4 - 20 TPI UNC-1A thread (and 3/8 - 16 UNC-1A for larger cameras) on American cameras. Perhaps in England the Whitworth form was used. Several variations of T-nuts and threaded inserts in these sizes are readily available over the counter in Ace Hardware Stores in America. David Goldfarb gives good advice above on mounting a T-nut so the tripod pulls it against the wood of the camera rather than relying on little screws to hold the T-nut as seen in some imported pinhole cameras.