It could well be the greatest conspiracy theory of them all. What if Santa Claus is not only completely real, but has been secretly 'played' by some towering historical figures of the 19th and 20th century: Rasputin, Trotsky, Franco and Elvis for four. All of those men needed to escape from their increasingly impossible lives, and with the help of shadowy government and regency networks in cahoots with a soft drinks monolith, they indeed disappeared to, maybe, Lapland, donning a big beard and bulging tummy to start afresh.

This wonderful slice of hogwash is the premise for Douglas Walker's latest ingenious and very funny Fringe hour. Playing all the roles with relish, displaying an acute ear for accents from Russia to American via 'possibly Norwegian', and penning a widespread of liberally sprinkled yuletide puns and references, his fireside tale rattles along at a satisfying pelt.

With previous Fringe shows, Walker (also a member of the Racing Minds improv gang) has shown off a desire for recalibrating the stand-up / sketch comedy form. Here he is content to simply conjure up a yarn which may be wild-eyed fantasy, but sticks rigidly to its own rules of engagement and offers up a delightful late-night treat.

Underbelly, Bristo Square, until 26 Aug (not 14), 10.50pm, £10–£11 (£9–£10).