Vorderman declined, and a search for a new presenter began while the show went into a four-month hiatus.
In October 2005, Des Lynam replaced Whiteley and co-hosted with Vorderman.
In January 2007 Des O'Connor replaced Lynam; Vorderman continued to co-host the show.
On 25 July 2008, after 26 unbroken years with the show, it was announced that Vorderman was stepping down from Countdown.
Vorderman recorded her last Countdown show on 13 November 2008 which was broadcast on 12 December 2008.
Both her children were in the audience, together with many of the previous guests from "Dictionary Corner".
During 1984-85 she made regular appearances on the Peter Levy show on Radio Aire, appearing mid-morning to read a story for pre-school children.
In the mid-1980s Vorderman worked part-time in the Information Services Department of the UK Atomic Energy Authority, principally in the production of in-house video programmes.
Initially, Vorderman's only contribution to the show was the numbers game, and she formed part of a five-person presentation team.
However, after the show returned from its summer break in September 2013, she began to host one episode per week, with Mc Lean anchoring the remaining four.
On 3 October 2013, it was announced that former Loose Women presenter Kaye Adams would be returning to the show later in the year and Ruth Langsford would join the panel in January 2014.
She began hosting the awards when they were first introduced in 1999.
In 2004, Vorderman took part in the second series of Strictly Come Dancing, partnered with professional dancer Paul Killick.