Marketform's Simon Lotter better hope his underwriting performance is up to scratch – his boss Holly Bellingham will be dangling him over the edge of the Lloyd's building on a thin rope tomorrow.

Lotter, the active underwriter at Marketform's Syndicate 2468, and Bellingham, the chairman of Marketform managing agency, are performing the stunt at 11.15am in an attempt to raise £10,000 for Comic Relief.

Lotter will shimmy his way up the outside atrium, and Bellingham will “belay” him while tied to the roof of the building.

Bellingham said she must have agreed to the stunt “in a moment of abject madness”, particularly as she is a 5'2 vertigo sufferer and Lotter is a 6'2 experienced climber.

“It started last Comic Relief Day in 1999 when, for a laugh, Simon walked around Lloyd's in his climbing gear,” she said. “We said we'd do something bigger this year.”

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