-
Do you need metal or plastic?
ETA:
It is also known as a flanged bush.
Have you had a look at the Simply Bearings website?
ETFA:
I've just looked on Simply Bearings website - they do them in steel or in bronze, as well as plastics.
I'm guessing that for your purposes the ID and the OD will be the critical dimensions (if you haven't got one, get or borrow a vernier gauge) the size of the flange less so.
-
Metal - thanks for the lead but found this guy making them on eBay who is making me one today which will be in the post ASAP as a temporary fix:
https://www.ebay.co.uk/itm/282625428793?var=581815641798
Thanks, that definitely seems to be what they're called but when I google that all I'm finding is ones for cars and motorbikes!
I'll keep digging unless anyone has any ideas...