Has never been age dependant, only mileage.
Current rates AFAIK
Up to 60kmiles = £1120, £886 & £731 based on 0, £100 & £250 excess, a slight increase from last year.
Over 60k miles = £2,680, £2055 & £1636 based on 0, £100 & £250 excess = those rates seem to have gone up a lot