Hello All. Thanks for the responses to what I had thought was a daft question!
An update on my limited progress: I was going to get some PlusGas, but it is not available locally (sure Halfords used to stock it!), but luckily copious amounts of WD40 seemed to loosen the spinlde sufficiently. I then proceeded to dismantle further and extract the spindle, which was very reluctant to come out. There seems to be no damage to either spindle or headstock bearing surfaces, but I am really surprised at how tight a fit it is when temporarily re-inserted – I have to mount the faceplate and turn the spindle whilst pushing it back in.
Now, from the condition of the headstock and the fact that the factory paint still covered the bearing clamping bolts, I am quite sure that the spindle had never been removed since its factory assembly, and would doubt the lathe had ever seen much use before I acquired it all those years ago!
So I have a new question: just how tight a fit in the bearings should the spindle be? Should I be able to spin it by turning the faceplate round? Or am I just witnessing 'factory newness' ?
(I should perhap add that this one of the earlier ML10s with plain bearings.)