21st Jan 2023, 03:09 PM
Hmmm, 35 mm across could easy be 3/4" or 1" considering today's 1/2 " and 3/4" bsp measure close to 27mm across.
Easiest way is remove the tap carefully so as not to dislodge the socket from the tank (usually soldered to the tank) then using something like a 5mm wide screw driver and hammer, tap at the corrosion inside the socket (caused due to brass tank tap inside gal socket) to clean it out then use a stick and rag to plug the supply while you take the old tap with you to get a new one.