Bike is too tidy not to be new. Enginewise it's still in break-in period. In spite of low mileage, tyres have been replaced. I would like to know the owner history, like how many? In The Netherlands you can find this out by the licenseplatenumber, but UK is maybe different.
This model has been the best tourer of all the CB500/550s by far and has offered me, 195cm tall, the best riding position. Suspension is superb and comfortable. I had opted for this model in 1980, but I didn't like the colour and its big blinkers and taillight which made it look cheap. However if the choice had been between this model and the 40 kilo's heavier CB750K7, I would have opted for the 550.
The silencers are well designed and very quiet, but lack the little drain hole for condens water previous models had. So... no short rides! As for the carbs, they are well designed, but since gasoline properties have changed, you have to ride it regularly. If not, by all means, add a fuel system additive like the one in the pic.