Soryy to 'come in so late' but I have been on holiday for a month. Well, I've really been on holiday for the lat 30 years
Martin Cleeve actually answered this question i 1953. He did and he actually fitted TWO motors to his ML7.
One was a a full 1HP and the other was a 1/3rd.Of course one CAN run a lathe of this size on a 1/4HP ex washing machine motor 1440RPM and I've done it.
Mine has ( well a S7B) has gone sort of three phase but given a fair wind and tide, it is getting a 1/6th 2880rpm as well.
Really, it is all academic, if push came to shove , you can pedal a 'M' series with a pedal and pitman. Time to buy a copy of old Sparey- methinks?