Hi both thanks for your comments,
Londongirl Leo often does have, what I call, 'sleepy dust' in the mornings such i have written off as normal for him. When he first had it months ago he was clearly poorly, he sneezed every 5 seconds and had a temperature and the conjunctivitis so that was sort of explained. When I took him just before Xmas all he has was a constant ball of yellow gunk on his right eye. The eyelid was pretty dark pink when the vet looked so he said it was conjunctivitis... now, today, it's gunk in both eyes constantly reoccurring again and when he was tired last night his eyelids were sort of visible if that makes sense and red.
Bizzlylizzy I did think about central heating , he dosnt sleep near a radiator in my mum's house but he does in my house and it's when we got back to mine that it kicked up again. I've moved his bed as far away as possible now but I assume now that they are irritated the infection takes hold etc and it needs treating. I'm going to question the vets about allergies tomorrow, however I am always wary of suggesting things to my vets as it is only then that they say 'oh yes that will cost £xxx.