Jonathan,
No it is the machine that's doing the tripping - everything else that runs off the circuit is fine and has been for all time that they have been run from the ring main. I have two different circuits/rings in the workshop on differentr trips in the main consumer unit, but this problem trips the main trip, not just the circuit trip. It is only when this machine is running - the lathe or compressor or whatever else has no problem.
Regards,
GeoffB