Would anyone know the age limit to rent a car in western Europe and British Isles?

To my knowledge, there is no set limit. It varies from country to country and among the rental agencies. You have to inquire.

I'm pretty sure that this is set by the rental company, not the country that you're traveling to.
I've read reports that although the companies do have limits, they don't really pay much attention to them. The problem would be if you had an accident....

Some companies will charge you extra if you are under 25. Just check a major U.S. car rental agency (Hertz, Avis) and their rules will be spelled out once you put a rental destination in.

For U.S. companies you do need to provide your age and driver's license number to them for verification.

As Joe Bob used to say, check it out.

Are you talking about a minimum or a maximum age?

Good one NeoPatrick!

I just take advice from Tom Waits on his song Phone Call from Istanbul "Never drive a car when you're dead".

"Good one" -- huh? That was a serious question.

We had some issues in some countries with rentals not being available to those over 65 or 70, but found they are to others.
But I'm not sure if that's what Ism is asking or if it's about how old you have to be to be able to rent a car.

NeoPatrick

Didn't mean to ruffle feathers....

I've never seen anything on a car rental form about a maximum age.

rastaguy: Upper (and lower) age limits can most definitely be a major problem. That was a serious question and no joke.