Richard and Judy first moved to Channel 4 from ITV, where they presented popular morning magazine show 'This Morning', in November 2001.
The move was initially seen as a mistake after they failed to imitate the success they enjoyed on ITV, where 'This Morning' regularly drew 3m viewers. However, viewing figures have now risen to around 2.6m.
During the first year at Channel 4, the show only drew between 1.5m and 2m viewers and the couple were reported to be considering returning to ITV.
However, since the beginning of this year, the show has drawn an average audience of 2m, rising to a high of 2.6m in February.
The change in the show's fortunes has been attributed to its celebrity guests George Clooney, Matthew Perry, Robert De Niro, Leonardo Di Caprio and Jennifer Lopez. It is thought the guests have appealed to student viewers, who made up a significant chunk of 'This Morning''s viewers.
Jo McGrath, the Channel 4 head of features who commissioned 'Richard & Judy', added: "It's been great watching the show grow its audience and its journalism to the point where it's a recognised success, attracting the best guests and the best stories and offering a real alternative to the soaps and quizzes on other channels at that time of day."
The couple are reported to have been paid £2m for the first two years at Channel 4. The new contract is thought to be worth around £1m.
Madeley called their decision to move to a new channel and a new slot "incredibly tough" and described it as the hardest thing he and Judy had done in their careers.
Finnegan said she was happy that they've got "at least another 18 months at Channel 4".
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