Old Steel Bike - Thoughts

Does the L'Eorica window move, is it 30 years?

If so, selling in 2018 and stating suitability for such event can also add value, you may end up selling it to a hipster with a ridiculous tash though!

As well as Retrobike you might try Cycling UK's forum in the 'Does anyone know...' section. Pictures are always helpful, but new forum members tend to have a problem with uploading images. Perhaps if you have an image hosting account - such as on Flickr - you could stick some photos on there and point to them in a link or series of hyperlinks. 

Harry Hall himself wasn't a frame builder but they (the shop) did make a few in house frames at the higher end, most of the frames sold through the shop were made elsewhere including Roberts IIRC. He had a big rep as a wheel builder though.

There's a glut of older frames (still) and many people hanker for new/shiny as opposed to the retro bike from any given era. However clearly there is a market for the older bikes but more and more people are getting fussy and/or are discerning.

Whilst the frame has a decent name on it pricing is difficult unless you know the frame material and finishing kit, a bog std 531 double butted (531C for the era we're talking about) then the frame in itself probably isn't worth a ton of money. Also one persons thoughts on 'very good', is different to another. The Campagnolo 7 speed groupset if in very tidy condition has a decent value to it and so if the finishing kit is decent and the seatpost isn't stuck in, wheels/BB rotate smoothly and overall in good nick it should be worth £300 easy and more to the right buyer, but that's a pure stab without seeing it or knowing more. Pricing is always very subjective.

Wait till spring to sell it though.

Have a look in here http://www.retrobike.co.uk/forum/