I've never heard of an employer caring that much about A levels when the candidate has a degree, unless the job is either one of the grad schemes which still requires x points at A level, or they're being used to distinguish between two otherwise identical candidates. Oddly, GCSEs can sometimes be more important, specifically the usual requirement of a grade B/C in Maths and English. It's unusual for a job to require specific A level grades in the same way.
This isn't to say A levels are useless; some employers will still care about them (there are bound to be some who really care about them), and even those that don't really care will still see them on your CV.