It's been common elsewhere for a while - and we'll probably get a better deal from bigger brands because of it.
When CR Smith sponsored Celtic it was huge for them - there sales were strong for years. Until, of course, the only areas left for them to sell in were the Protestant areas of Glasgow and Edinburgh. When British (sorry Scottish up there) Gas were recruiting field sales teams they found whole groups who had been massively successful selling double-glazing for years only to find they couldn't find anywhere else to sell it.
Tennants didn't make the same mistake.
Strange to think that half of Sheffield would make enough difference to someone's sales - Gilders I can understand, I didn't realise Westfield were so local (I knew they were on Division Street - I meant their customers).