Davina McCall has been criticised by UK media watchdog Ofcom for using the word "retard" on spin-off show Celebrity Big Brother's Big Mouth.
The incident occurred in January, on the same night as the finale of the last ever series of Celebrity Big Brother.
Evicted housemate Vinnie Jones first used the word when he talked about McCall entering the house in a chicken outfit.
Asked how he knew that the person in the disguise was McCall and not Nicola Tappenden, he demonstrated walking with difficulty and told Celebrity Big Brother's Big Mouth: "She was walking like a retard, she was walking like this and our Nicky walks lovely."
McCall responded: "I do not walk like a retard."
Ofcom received eight complaints about the ex-footballer's comment, with seven viewers also offended by McCall's response.
Some said the Big Brother presenter had appeared to enjoy the 'joke' and did not reprimand the movie hardman on the E4 show.
Ofcom originally did not uphold the complaints and received letters of protest about its decision.
Later, it decided to hold a review by referring the case to its Broadcasting Review Committee.
Today it stated: "It was the Committee's view that his (Jones's) use of the word 'retard' was capable of being understood not as merely a passing reference directed towards Ms McCall but also as ridiculing those with a physical or learning difficulty, emphasised by his attempt at imitation.
"The Committee was particularly concerned that not only was Mr Jones's comment not corrected but that it was repeated by the presenter, Ms McCall, without any apparent recognition of its potential to cause offence.
"The Committee, while acknowledging this was a live show, considered that in this instance the action of Ms McCall had the potential to heighten the offence to viewers."
The Committee said it was "concerned" that the programme-makers took no action during the programme to seek to mitigate any offence caused.
That "failure suggested a lack of understanding during the live broadcast of how offensive the comments had been", it said.
"In the circumstance of this particular case, there was insufficient context to justify the offence that was likely to be caused by the comments made during the programme. Therefore the broadcast breached generally accepted standards."
Channel 4 said the comments had been allowed to go unchecked "in the heat of the moment during a live programme" at the end of a final eviction day.
Learning disability charity Mencap welcomed today's ruling, saying over 750 of its supporters wrote in protest to Ofcom after it originally did not uphold the complaints.
It's chief executive Mark Goldring said: "We are delighted that that Ofcom has changed its mind on this matter.
"The groundswell of protest and emotion caused by Channel 4's broadcasting of this insulting word has demonstrated just how offensive and degrading a term it is.
"Ofcom has done the right thing in taking this opportunity to set a standard and make Channel 4 take responsibility for its mistake."
© Press Association