Objectively, it is a good colour with full service history, any other details on spec, extended warranty, Bucket seats, DCC?
Obviously mileage will impact the value and I feel a standard car is easier to sell than a mapped car. A Revo map may be a positive for some buyers, you only need one buyer after all!
Without full details on spec and what may be needed soon, such as tyres etc.. It's hard to be specific on value.
On what we know I would put the car up at £21k and hope for >£20k with a private sale, the mileage is the major determinant.
I think the above "guesstimate" may be slightly optimistic due to the rarity of the car, especially at this price point. We don't have many £20k CS available as yet!?
One thing you can be sure of is the trade bid will be at least a couple £k below that.
(I have a 7.3k mile CS and follow the market on these!)