Drive this discrimination off the road

When we moved to live abroad for several years we sold our car and hired one when we needed it. But when we returned to the UK we found it impossible to hire a car - with the exception of one car hire company to which we had to travel by bus because insurance companies put a block on car hire for anyone over the age the seventy.

After driving abroad (left hand drive), on every return visit to the UK we had no problem driving a right-hand vehicle, before being banned by insurance companies, which is ironic given that they pay out far more for accident claims for the under 70s than the over-70s.

So what can I do about being age "discriminated" against?

E. Wolk, Suffolk