The broadcaster is calling time on the show which was first broadcast in 1984.
The singer scored the highest total of the series so far on Saturday night.
Cheryl, Mika, Stormzy and Jack and Kelly Osbourne are this year’s guest judges.
The British star briefly quit Twitter after critics called for an Asian actor to play the lead role.
It appears that the two will make amends over lunch.
The singer shares stories from her life and career in the special documentary.
The gloves are off between the presenters in the new Saturday night competition.
Competition is hotting up in the final stages of the contest.
Abbey Clancy celebrated with the new contestants.