Many thanks for your suggestions Steve. I'm south of Gloucester.
There was no sign of loctite previously being used to hold in the old bearing. However, as you'll see from the photo, there were 4 spot punches - the bumps of which must have been polished up by the outer wall of the bearing spinning round inside the hub.
I had a look at the Loctite web site today and the 461 bearing sealant is good for gaps up to 0.2 mm (as long as its given 72 hours to set). I think some of this along with several more spot punches interleaved with the existing ones should do the job. What do you think?
Pete