The glamorous mental arithmetic queen, who has an IQ of 154, has been a popular figure on the afternoon quiz since it began 16 years ago. She has now been signed up by the channel for another five years.

Known as the brainiest woman on the box, she speedily works out long complicated sums in her head, checking whether the contestants have an accurate answer.

The show regularly attracts more than four million viewers and is daytime TV's highest rated programme. Channel 4 executives say that the key to its success is that it appeals to both students and pensioners alike. The show also has an important place in Channel 4 history - it was the first ever programme broadcast when the channel launched in 1982

'Money well spent'

Ms Vorderman will net £1m for working on 255 episodes per year. This involves just 40 days work per year because the producers, Yorkshire TV, record the shows in batches of six or seven a day. The deal means that she has achieved financial parity with her counterpart on the show, Richard Whitely.

A Channel 4 spokesman said: "It's money well spent. Carol is an enormously valuable asset to the channel and we are very pleased that she will continuing in this role for us."

Unusually for a TV presenter the 37-year-old mother-of-two also fronts prime time shows on both ITV and BBC as well. This takes her total earnings to more than £2m a year and makes her one of the highest paid people on television.

Ms Vorderman's career has gone from strength to strength since the low point when she was dropped by the BBC from the science programme Tomorrow's World over her involvement in advertising washing powder.

She currently presents the TV programme Mysteries for the BBC, and from January will be in a new BBC series, Dream House, with EastEnders' star Adam Woodyatt.