Former Channel 4 racing pundit John McCririck is seeking £3m in damages from Channel 4 and IMG Sports Media for alleged ageism.
It was announced in October last year that McCririck, 72, would be replaced as the face of Channel 4 racing this month by 41-year-old Clare Balding. McCririck had been associated with the programme since 1984.
He said in a statement: "Channel 4 and production company IMG Sports Media were yesterday each served a letter before action for age discrimination.
"After 29 years with Channel 4 Racing, on a rolling annual contract, I have been sacked without any consultation or cogent explanation. I am 72.
"For loss of future earnings, unfair career damaging, public humiliation, stress and mental anguish, I will be seeking £500,000.
"Ageism is illegal. For tens of thousands of employees it has become the feared scourge of our society. This litigation should prove to be a watershed.
"There's no upper limit to the amount of damages employment tribunals can award under the Equality Act 2010.
"I am seeking a further exemplary, punitive £2.5m, part of which will be donated to charitable organisations helping to prevent negative prejudice in the workplace."
It is understood McCririck is being represented on a no-win no-fee basis in the action.
Channel 4 is yet to comment on the action. IMG Sports Media declined to comment.
Outside of racing, McCririck will be recognisable to Celebrity Big Brother fans after a memorable turn in the house during 2005 – it was a performance so good that it earned him a place in the Ultimate Big Brother house in 2010.