Shakin' breakin'
 

My brakes have developed a shake that is quite noticable through the steering column, but only between around 70-60mph. Above and below that, it seems OK. I've had the wheels re-balanced (one was about 25g out) but the problem persists.

Is this a nasty surprise lurking?:(

Warped disc would be my first bet......

I'd agree with Ian but could be something obscure like tracking out causing uneven tyre wear and that then causing the vibration. I just replaced front discs and pads on mine and it's sure helped vibration issues +++

I had something similar, was cured with new bushes

Sounds like a trip to A4 Audi for a service and check-up :(

But the tracking is out - the tyres are scrubbed a little on the inside

And no-one pointing out that the title of the post should have been Shakin' brakin'? I don't usually get away with poor spelling! :)

Warped disk would affect all speeds. It's more likely to be worn suspension bushes.

Just passed its MOT though - should that have been at least an advisory?

Should have been..

You could try a couple of big stops (and I mean big... 100-0) and see if that clears it up, could just be some crap caked on the disks, had this on the volvo once.

Also check tyre pressure. I get wobbles now and again if the pressure is wrong.

and get the balance re-checked :)

I have exactly the same problem with mine - not serious, only happens with firm, steady braking at that speed. It's now had the discs and pads replaced twice in the last few weeks by Kwik Fit, who couldn't find the cause, and it's also been checked by Audi Stockport, who recognised the problem, but couldn't identify the cause. I now only brake either hard or gently, to avoid this :-(