The chain is using classically trained actor Karl James to instruct wait staff in the fine art of conversation, and how to butter customers up so that they spend more. (I'm guessing that Pizza Express probably didn't have too much trouble finding James, considering that like most actors, he was probably already on the wait staff.)
Interestingly, the chain felt that running these sorts of courses was necessary because technology and social media are making us completely inept at conversation. According to a source close to the company:
With social media and texting reducing our face-to-face interaction, Pizza Express has enlisted the help of a conversational expert who is incorporating flirting and unique conversation techniques … into its new staff training scheme to help completely redefine the restaurant experience for customers.
The best part of this whole story is... that it's actually a story. I've known a number of waitresses and bartenders in my time and this sort of thing would not come as a surprise to any of them. I hate to break it to The Telegraph, but flirting with your customers to weasel more dollars out of them is a time-honoured tradition in the service industry.
Still, I may just pop by a Pizza Express while I'm over in the UK in a few weeks just to see how far they take it. According to the story, staff have probably been warned not to get carried away. "If they mean customer flirting in the sense of 'what are you doing later when the kids are in bed', that's not a good idea," said one observer.