Nigella's double helping

Nigella bites - slowly, ever so slowly, into a single sprig of parsley.

A lock of her midnight-black mane falls across her face but with the practised assurance of a seasoned pro the coquettish cook stares on into the camera - a seductive glint, as ever, shimmering in her deep brown eyes. Boiling point is just a gas mark away.

Except this isn't Nigella at all. It's Ronni Ancona, the uncannily accurate impressionist who has already unleashed devastatingly on-the-mark parodies of Carol Smillie and Posh Spice - and who turns her attention to Nigella Lawson in the new series of Alistair McGowan's Big Impression.

The series will also unveil new impersonations of Neil and Christine Hamilton and Anne Robinson - and bumbling TV interviewer Louis Theroux is lampooned in a magical sketch called Louis Potter and the Philosopher's Stone.

Lawson is famous for dousing all her programmes with a liberal portion of sex-appeal, and Ancona spent weeks studying her languid mannerism.

"I always have to find my take on what drives a person before I feel happy that I can do them properly," she has said.

"You can't improvise on a musical instrument until you've mastered the fundamentals and have something to build on, and it's the same principle with an impression."