WBAC give a very cheap price, it goes through the auction at £500 more than they've bought it for, or maybe £1k depending on age/condition etc. The used car dealer then puts another £1k on the price and hopes there's nothing terminal wrong with it to eat into that profit.
My car (62 Plate Mk 3 Focus Zetec S Ecoboost 182, just ticked over 60k miles) is on WBAC for £5,110. There are older Mk 2 Focuses (Focii?) with higher miles up for more money both privately and from a dealer.
This one is very similar. Same age and roughly same mileage but mine doesn't have the red interior (thankfully. Ewww), heated seats or rear parking sensors. Both very rare options but unlikely to make a huge difference in the price, perhaps £200. Mine does have four still good Continental tyres though!
It's up for a £5 shy of £7k. I wouldn't expect to see a car similar to mine for less than £6k easily, more likely £6.5k and perhaps beat the dealer down by a couple of hundred. There's £1k or more in there to be split between WBAC and the dealer.