My father had one, nice bike, 531 frame etc. Being an old school kinda guy, when he decided to sell he did the 'right' thing and refurbished the bike with super cleaning, oiling , adjusting, new tyres and chain before offering for sale. It looked super. I think he advertised it for a couple of hundred quid but no takers. In the end it went to auction and fetched about 30 or 40 quid, less than he paid to refurb it. Nice, practical, good quality bikes but just not that desirable i'm afraid. If yours need work they'll only be worth pocket money.