106 wont start?

i have an 'R' reg pug 106 and it wont start, it turns over but only slowly and i have had the battery charged off the mains, it worked once but never since, i have bump started and this used to work but not so well now and i have jump started it from another car and this worked well but now takes a little convincing. the battery is holding its power and once its started for the rest of the day the car will start with no probs but getting it started is i nightmare and i have no idea whats wrong with it.....