Looking at various ways to fund a S7 edge, this was the best deal I could find for one of the established networks (approximately £90 cheaper than buying new). The phones apparently haven't been used for more than 14 days (in accordance with the returns policy) and come with 12 months warranty. Anyway, if the condition isn't "as new" it will be going back. Vodafone network.
Also possible £30 Quidco (which I forgot about, grrrrr).
500 minutes, unlimited texts, 500MB 4G data.