I'm definite that the taxi driver for the Shepherd's Bush trick was a stooge. I mean, it's one think to do a psychological force of a card but a totally different thing to force any area in London. Then the £8 - that was unforceable :S.
If I remember correctly, the taxi driver didn't hold the envelope all through the effect.
And as for the envelope and the £1000, I'm sure the envelope had something written on it when she opened it. Perhaps 'don't change your mind'?? Or maybe I have been reading Corinda too much recently.