Sorry lost the OP's post, but I had the same problem. Found in the Grainger catalogue (US) a Dayton AC/DC series motor, model No. 3M037A, 1/10 hp, 1.5 Amps at 8000 rpm. It is of course 110 volt, 60 cycle, but I'm sure there must be an equivalent for the UK. I put a light switch dimmer control in the line so I have speed control without moving belts over pulleys, works like a charm. I also mounted it on a little fabricated angle so that it was to the left of the pulley which made the space behind the chuck free and MUCH easier to work in.
This outfit handles Dayton motors in the UK:
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Mike in BC