Can put some photos up Steve? Headstock, front gearbox, and whatever tables are available. Click this link for this forums photo HowTo.

The photos will probably contain enough clues for a forum member to suss it out.

Also possible to do it yourself from first principles. Put a rod in the chuck and arrange a knife or felt-tip pen in the tool-post so it just scratches or marks the rod. (Metal, plastic, wood, whatever, about 25mm dia so you can see it). Engage the gearbox to cut a thread and turn the chuck several times by hand to draw a spiral on the rod at least an inch long. (Quicker and easier to do with coarse threads than fine ones!) Then measure how many turns fit in one inch with a rule. If the lathe is set for imperial there should be an exact whole number of turns between the inch marks. A spiral that doesn't fit exactly inside an inch strongly suggests the lathe is set up to cut metric pitches. Repeat the test with a couple of different gearbox settings to confirm. Necessary because a few metric threads are close to imperial.

If not tpi, measure the distance between two turns in millimeters. Then loolk them up in a table. For example the threads on an ordinary M10 bolt should be 1.5mm apart, ie M10x1.5pitch. M12 coarse threads are about 1.75mm, and M6 are 1mm apart.

Once the spiral is identified it should be possible to relate it to the gear setting tables, and it should make sense.

Dave