Well we ended up bringing him in (we have plumbers in at the moment and the baby was up so couldn't just leave the house lol)
His little marbles seemed to of dropped since yesterday, maybe the warmth of the house helped?? I tried with a bit of twine which seemed to work until I tried getting the band on. In the end I managed by pushing the applicator towards him a bit harder and pushing on his tears to make sure they didn't get ringed.
So glad it's done now and I don't have to worry for another year!