I would not guess 531db on this frame. Steel Cranks and probably cheap simplex derailler on rear do not indicate much in the way of "high end". Nice english lugs, a la Raleighs of almost any stripe. Looks to be low to mid range ride, think Raleigh Record or Grand Prix, or Peugeot UO-8. Someone has upgraded the bars and possible brakes, but the frame makes the bike, as they say.