Only the bravest thrill-seekers will be allowed into Chessington World of Adventures’ scary new attraction, Creepy Caves Unearthed.

Guests over 35 will be put through three Brave-o-meter tests, being spooked by park staff, and if heartrate tests show they have kept their cool, with their pulse remaining under 100 beats per minute, they will be let in.

The theme park has conducted research that suggests people at that age are far less brave than their younger counterparts, with 83 per cent of under-35s describing themselves as brave, compared to just 14 per cent of older people.

Jordan Smith, Brave-o-meter coordinator at Chessington, said: "Creepy Caves Unearthed is set to be our scariest attraction yet and, while we're expecting children to be brave, our research shows that adults' sense of bravery dips after 35.

"We want to ensure that everyone who enters Creepy Caves Unearthed enjoys their experience, and the Brave-o-meter tests are designed to put those through their paces and really get a sense of how much Howl'o'ween spookiness they can handle. Creepy Caves Unearthed isn’t an attraction for the faint-hearted, so it's vital that we make sure over 35s in particular are fully equipped and pass the tests before they enter."

The attraction is set in a quarantined area, where guests will be led by secret agents in a search for clues about why zookeepers are disappearing.

Tests will be tried out at the park’s “Howl’o’ween” preview on Thursday, October 19, to be carried forward throughout the event if they are successful.