Robert Plant ?

... any specifics about Bob Dylan go a bit grey with me.

Thomas Tank and not doing autographs any more, that's about it.

Now we all live in a Michael Jackson/Madonna/David Beckham theme park I think it would be too frightening to contemplate quite how little is known about, say, Bob Dylan.
So I don't contemplate it.

The general public know Elvis and could describe him (as he looked at the start of his career) but probably could name only a half dozen of his songs at best

I'd say that statement applies to the "other" Elvis as well..

I'd imagine quite a few people would recognise him without being able to name a single one of his songs. Maybe Laughing Len too, even after "Hallelujah."

And I'm sure a huge proportion of the population couldn't name a song by Led Zeppelin, and could only name "Another Brick In the Wall" from Pink Floyd. Good calls on Neil Young & Dylan above too.

Some song about turps (meths? White spirit? Something like that, anyway), underprivileged hair, an appalling wife and a shotgun - the stuff of which legends are made.

Plus, I suspect for 99% of the population David Bowie still has bad teeth and wears knitted bodystockings, and, as for Richard Thompson, isn't he Emma's dad and wasn't he involved with The Magic Roundabout in some way?

Sandra Bullock and Jeff Bridges won the Oscars, but how many of their films could the general public, which includes me, name? I deliberately haven't checked Wikipedia, but I think Sandra Bullock has been working for about 20 years, and I know I've seen her in something but I can't remember what. Jeff Bridges, who must have been in films for over 30 years - and I think he's good - off the top of my head, The Big Lebowski, The Fabulous Baker Boys, one with Clint Eastwood, and Cutter' s Way (I think).

As for earlier generations, well Brigitte Bardot is still very famous - not sure what she was in apart from Doctor at Sea.