I have aquired an 2nd hand Astra Cast monobloc kitchen mixer tap. It came with the horseshoe fitting but no tap tails. I've taken it to several plumbers merchants to try and buy these, but the threads on the tap appear non standard. Neither a 10mm or 12mm flexi pipe will fit. The 12mm is close, but binds before the connector is fully home so the rubber washer on the connector does not meet the tap body. Has anyone any ideas what the thread size could be and where I could get tails from?