[arethuza]

Good point - I believe U2 pilots need to be talked down the last few feet by someone in a chase car:

http://jalopnik.com/5537629/the-140-mph-chase-cars-of-the-us...

Maybe U2s were operating from RAF bases and they thought it was polite to use US cars?

[walshemj]

The US RAF bases where little piece of America in the UK vehicles drove on the right.