I caught an early easyJet flight from AMS to LTN several months ago. The number of "suits" who then strolled over to the Silverjet terminal was very interesting.
Why hub out of LHR if you don't have to? I use LHR for positioning flights too often for my liking and it's dire. Too crowded, too congested, not enough staff. I am not questioning the safety of LHR, but the convenience.
If given a choice between Silverjet from LTN (20 min from my house) versus BA from LHR (esp T4).. Easy decision.
As for the add. Cheeky. Like it. Remember the first one and was impressed. Like the Silverjet one as it makes a very valid point. The catch phrase needs work but I am sure they'll sort it.