The strategy makes sense IMO. I think it was a mistake to take a well-understood brand like Freeserve and replace it with the unknown and odd-sounding Wanadoo. Replacing it again with a very powerful brand like Orange will benefit them, and the ability to bill customers on one piece of paper is a powerful selling point (as well as a big money-saver for them).
Me, I won't me going with them when we finally get ADSL next month. It's Zen for me, they come highly recommended, and entirely uncapped.