I think the offical answer is yes, depending on how they are used. You might be interested in taking a look at a page I've been playing with recently at
www.dragonfly-sameday-courier.co.uk\local.php?area=coventry
In theory you can change the area to any uk town, try it and see. Let me know if you find any towns that you think should be there and aren't or are in the wrong place etc. I've really only got a test list in at the moment.