Well have kept it on since I first posted, and he has got the serious hump with me now!!
He has retired to his crate and can't be tempted out with any toys or cuddles - he just glares at me as if to say "p*** off - you've put this horrible thing around my neck!"
He has resulted to rolling all over the floor to try and get it off. Am going to give him another hour and then take it off for the night, but back on tomorrow until he gets used to it.