Have you considered the Refurbished - New Life Edition @ £385 upon which I couldn’t find a mark on my example and still get 2 Yr warranty?
https://www.thephone.coop/personal/phones/fairphone/Refurb-FP2-Handset-only/
As you are in the UK you might like to follow this Ebay auction (last three FP2 on Ebay sold from £240-330 dependent upon condition and time of day auction finished), although absence of seller feedback may be discouragement from bidding:
http://www.ebay.co.uk/itm/Fairphone-2-Brand-new-boxed-and-unused-/182698402031?hash=item2a89ac60ef:g:KhQAAOSwsjRZgZ3-
You would have time to discuss with seller whether prepared to transfer warranty to successful purchaser following this resource:
Process is explained here: How to safely sell or buy a second hand Fairphone