House was fitted out in JG Speedfit pipework which I was very sceptical about having been a traditionalist copper fan.
Installing monobloc taps on the bathrooms. Tails came with traditional 1/2"BSP. Instead of spending £10+ on a set of Speedfit tails, I used these to connect between the supplied tails and the plastic pipework. No leaks at all (which I could say the same for the isolation valves 32802 which I used on the toilet cistern supplies - these were notoriously difficult to seal)."