I have a shuddering feeling in the brake pedal when the brakes are applied. If applied hard it's worse and you can also feel it thru the steering wheel.

What causes it and what's the best thing to do to fix it?
All the brake pads, front and rear, the front rotors and the bearings where new about 20,000 k's ago and the front calipers where reco'd at the same time. The pads are a bit over half worn now.

Any ideas please? The car is an EA GL auto

Sounds like your rotors are warped, very common problem. If they are new then they should be thick enough, you can get them machined. Or you may need to replace them (about $75each) Remember to replace the brake pads also.