Coronet Major Lathe V-belt. The correct section UK or EU-made V-type drive belt.
This is the belt for the earlier Coronet Major - the later Model had a "Poly-V" belt - flat across the back and with multiple small Vs on the drive side. This belt can be ordered here: https://store.lathes.co.uk/parts/coronet-record-major-lathes-late-models-drive-belt