I understand now.
I thought you meant something different when you wrote
I thought ' fall out' would mean 'removed'. i.e. we are looking at Feb 2010
Anyway, I think it’s fair to say the Halifax figures at the backend of 2009 were surprisingly high. This was possibly caused by the Stamp Duty holiday, but at the same time it could also have been caused by the mix adjustment method used by Halifax. Given that we don’t actually see the ‘mix’ we can’t verify that the method is being applied properly. This means that Halifax could* adjust the mix to give them the best Christmas bonuses. Don’t be surprised to see some shockingly high figures again.
* In theory only. I’d never accuse them of actually tweaking the figures to suit their bonus requirements.