Lidl had in today swivel castors set of 4 with 2 locking for £4.99. I bought 3 packs to for the remaining items in my workshop that are not mobile. They are 2" diameter, maximum load 25kg per castor and very well made at a bargain price.
https://www.lidl.co.uk/en/Non-Food-Offe ... cleId=4921...