I've seen Reynolds 653 complete bikes with decent specs go for 200 on eBay. I think you're looking at 120-180 max for this. Nice condition but nothing special apart from that.
Are you the original owner? Did you buy it to sell?
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Seconded. Around 120-140 GBP seems fair.
For comparison, check this: http://www.lfgss.com/thread110798.html#post3737385
Vitus tubing, high-end Gitane (french, 80s, great condition), with more than decent components, asking less, including postage.