Those 3K valuations are somewhat pie-in the sky! The car does look nice, but the owner unfortunately now has an unrealistic figure for their car and could struggle to even get anyone to look at it!
To me, from those pictures, the paintwork has visible blemishes- look at the boot lid-
Possibly the paint job done last year was not all that good (£700, 2K blow over.perhaps?), or maybe the car just needs a good clay and wax. The interior looks worn, the red battery looks incongruous, a black "period" looking classic style battery would be much more fitting, the wheels are dull black and if the underside "corrosion work" done was just local garage MOT style overlapped patches then this car is not worth anywhere near the £3k suggested. The car looks to me to be a good condition 2 car, i.e. fairly solid but needing tidying, and if the car is as I think it is, then £1500 -£1750 is more like the mark. With a years MOT, of course.
To get to £3K+ his car would need the paintwork done again, this time from bare metal, the underside to be properly repaired (assuming the corrosion work was just patches) and the interior tidied to get closer to the £3K.
Sorry if my assessment seems a little harsh, but the OP did invite all to "hazard a guess"!