As well as official Bilderberg members, the conference is also likely to attract a number of uninvited guests, in the form of protesters, alternative media and conspiracy theorists.
The crowds attracted to the annual meeting have swollen from about a dozen when it took place four years ago, to a reported 800 people last year in Virginia.
Most of The Grove’s grounds will be closed to the public while the conference takes place and Hertfordshire Constabulary will be given the job of keeping the crowds out.
The main attraction for the crowds will be the arrival of the guests to the meeting.
In past years the official list of guests, which is published ahead of the event, has been widely rubbished as a “smoke-screen” by people who then attempted to discover and reveal the conference’s true guests.
In 2012, photographers eagerly awaited the arrived of the black limousines which ushered their secretive passengers into the safety of the Westfields Marriot Hotel, in order to identify the main players and draw conclusions about which subjects will be on the agenda for discussion.
Among the reporters were demonstrators with loud-hailers, shouting protestations at the cars as they weaved past.
In the main the crowds were kept confined to the lawns outside the hotel, and although the barriers were strictly enforced, there were no reported arrests.
Whether Watford can expect the same crowds is yet to be seen.