Clueless About Portmeirion

The description said only 'Portmeirion, Wales', and other tags added, 'the prisoner, tv, show, and cult'. The big white balloon is another clue.

Attack of the Rover! © Flickr user Dellboyy Art under Creative Commons.

According to 24 Things To Do in Portmeirion, United Kingdom (virtualtourist.com),

The ground in front of the Pavilion was used as the giant game of chess in The Prisoner.

So the balloon was called Rover?