OK, problem seems to be solved, this is the process l followed but am unsure how l arrived at a successful ending.
l have an earth lead from bat neg to alternator brkt bolt and 1 from bat neg to the radiator support. l removed both and cleaned / sanded connection point, still just running very slow off the key. Next l thought l would test the integrity of either. l removed the lead that goes to the engine / alt bolt, still the same,re connected and then removed the lead that goes to the rad support. BINGO started like a champ ! Tried it a few times, warmed everything up, started it a few more times, all OK. Re connected the bat neg cable to the rad support and it starts fine. Out for a drive and a few stop starts and all OK. So l will be stuffed if l know......a dodgy earth somewhere? Thank you for every ones input, cheers