I'm a bit more at home with Raleigh cycles (this Lotus and a Fuji Team which I acquired last week are the first Asian bikes I've owned). Anyway, with Raleighs built from high end TI-Reynolds tubing, the seat post diameter usually gives an indication of the tubing type. Frames made with 5-3-1 generally take 27.2mm seat posts. The frames built with 7-5-3 take different sized seat posts depending on whether the 7-5-3 tubing is metric or Imperial sized. I don't know if Columbus tubing varies in a similar fashion or not but if so, that may also provide a clue for sussing out which tubing was used for the Legend model frames.

As for my Supreme, Sheldon Brown's site indicates that it should take a 27.2mm seat post. I'll soon know whether or not that is correct and will report back with that bit of data. Perhaps if all Lotus owners start measuring various parts of their bikes a data base can be established to help ID future bikes that reappear.