Should you be entitled to privacy in a restaurant? What is the threat?

I went for a lovely meal yesterday with family and friends and was somewhat surprised to see the following sign on the wall - I have removed the third party's contact details hence the blank areas:

It wasn't the most expensive restaurant on the planet but nor was it low rent either. I can't for the life of me work out WHY ongoing surveylance was required - surely this is privacy invasion gone mad. I don't have anything to hide - particularly at meal times(!) but nonetheless I do object to the incredible number of privacy infringments that UK citizens endure on a daily basis.

I wonder what background checks are done for those that get to watch me eating my dinner? Who validates and verifies the operating procedures of such individuals? I wonder who's monitoring those who are watching me eat my dinner?

Seeing as goodness knows who knows what I ate for dinner yesterday I may as well publish on the Internet that I had a Lamb Shank with Broccoli, green beans, mashed potatoe and mint sauce together with a glass of sugared carbonated water and an expresso!

Upon further observation it wasn't too hard to identify the locations of the "hidden" cameras. The really bizarre thing was that the till/cash register seemed to be outside their scope!

Note: I discussed this post @ lunch today and someone suggested the cameras may be present in the restaurant to inform the parents of those who don't eat their vegetables!