Well is'nt just sods law, I went to the tool stall on a local market and asked the guy if he happened to have a 5/8" tap connector, he had something better than that, he had one with two adapters 3/4 and 5/8". I bought a couple for a quid each.
This little orange adapter allowed me fit a 3/4" Hozelock pro stainless steel connector. I have just spent £20 on adapters, and found exactly the right thing for a pound