In reply to Mattyk:
We did the usual 3 quotes and went with Yorkshire windows from Bradford.
No high pressure sales, the guy measured up and left and posted the quote to us the next day with the promise that they would not contact us if we did not contact them first unlike the other 2 guts who I came close to physically ejecting from the house, both went down the "this is a special price just for you as we want a show house in this area" route.
Yorkshire was also no deposit 100% payment on satisfactory completion.