Thanks Charm.
To be honest, apart from his bottle, he tends not to drink that much at tea time, he's more of a 'wander round after lunch drinking' kinda guy.
I've tried cutting the inner nappy a bit differently from how I was doing and that seems to be helping with the leak issue. Plus DS has started occassionally holding himself so there will be a little bit of wee but not much, and he wakes up early busting for a new nappy (he is still sooo tired when this happens so much to grumpy to sit on the loo).
Thanks for the thought. If (ha, I mean when) his nappies start leaking again I may try offering him water a little while before his tea so he has time to pee out before bedtime.
He leaks from legs, tummy, you name it but no big leaks for a few days so I'm hopeful.