Over the last few months the Groupon war has been moved to the UK and in particular London. Groupon was the first company that started in 2008 in Chicago. The way this works is very simple:
This model was rolled out to other several cities and since January 2010 there are at least 10 groupon voucher websites in the UK! Compared to the the size of the UK cities there are way too many websites. Some of the sites are extremely popular, some others merged in the mean time.