Set designer Michael Vale has filled the stage with crazy contraptions.

In the show, Gretel is an inventor whose creations help the children escape the witch.

“At the end the witch is going to cook Hansel and she asks Gretel to check the oven’s hot and she says ‘no, I can’t fit in’ and the witch says ‘even I can fit in’ and they close the door,” says Grose, who plays the witch as “Fanny Craddock dissolving into a monster”.

“We always thought that was a bit lame as the climax to the show so Mike wanted a chain reaction device that Gretel had been making.

“They’re really good fun because we never quite know if they’re going to work so there’s always a moment of tension.”

Grose wrote the play at Kneehigh’s base – a series of National Trust barns near a beach in rural Cornwall.

“It’s a really good place to get energised and strong for the show because it can get quite hectic,” he says.

“There’s definitely a spirit that all of us share about making works so when we’re devising the show we enter into it with the spirit of play and the barns are a great place for that.”

HANSEL and Gretel is at the Liverpool Everyman, March 16 - April 3.