Minispares own product - R/H to last Rover drawings.
Call it a hub, bearing carrier, upright or swivel pin, on the Mini it's all the same thing.
You'll need these (FAM2391=left, FAM2390=right) new hubs if you are converting to disc or "if your old hubs will no longer support the bearings properly". All new and ready to use. Either replace your old one or start a kit to convert to disc.
THE original BTA186 with chamfered end is 72MM in external width where the bearing sits but FAM2391 with step on end is 75MM wide to stop bearings flexing with bigger wheels. (THIS WAS ROVERS THEORY)