It's time for a rant about SACAT. "About what?" you might most reasonably cry. 'Semi Attended Customer Activated Terminals', that's what. In plain English, it's those self checkout things that are taking over shops up and down the land. In 2008 there were 92,600 such units in use worldwide, by the end of this year it is expected to top 430,000. In the UK, 32 million shoppers now use them every week, over one third of Tesco's store transactions every week are self checkout. I recently went to WHSmith at St Panchras station in London, the first shop I've been into that is 100% self checkout. No staff. I turned around and walked back out again.