Steering vibration was starting to come back after a few days and was gradually getting worse. This was during normal braking.
Took it to another local dealer who fitted new discs and pads to the front saying that the 'recently fitted new discs' were out of tolerance after doing less than a thousand miles.

Now I'm happy to report that the car drives like new and there's not a hint of judder when braking.

This is quite a shocking story, both the initial botch and also the response.

I just can't imagine changing pads and not having the pin through the hole, and I'm no professional mechanic. They should really have got back to you with an explanation and how it won't happen again.

After I had emailed my concerns to Mike, I received an immediate response from the Service Manager who apologised profusely and shared my concerns.
I reached an agreement to have its next big service heavily discounted (although all it will be costing them is a few pounds for parts and free labour).

Ok, that sounds more reasonable.