Been down to the plumbers merchants and had a brevitt and come up with:- 1, 3/8 bsp male staight connector, 1, 5/8 male to 3/8 female reducer, 1 5/8 female straight connector and 1, 5/8 male - female connector and the landy sensor fits, seems a long way round it but it works and cost a fiver, hope this helps anyone trying to do the same.