1940s Fothergill, 1959 Allegro Special, 1963? Claud Butler Olympic Sprint, Lambert 'Clubman', 1974 Fuji "the Ace", 1976 Holdsworth 650b conversion rando bike, 1983 Trek 720 tourer, 1984 Counterpoint Opus II, 1993 Basso Gap, 2010 Downtube 8h, and...
You might find some indication of both model and tubing on the steerer tube. Mine has REYNOLDS 531 stamped on that, apparently by the Reynolds factory, and 720 apparently cut by hand with a Dremel or similar, apparently at Trek. And yes, it's a Trek 720.