Many thanks for all of your comments.
Non return valve had already been fitted last year but nothing changed. We flattened the battery trying to start the car having jump started we went for a run and decided an electric pump should be the solution. Next morning, battery should have been charged but didn't show much life, but car started immediately using a new battery destined for the 2CV!, so we decided on a new battery as the old one was at least 12 years old!
Car has been much better since then, a bit reluctant if stood a while but that could we think be user error!
Thanks all the same!
