The 73-year-old pundit - known for his flamboyant clothes, tic-tac gesturing and gold jewellery - believes he was "sacked by anonymous suits and skirts" because of his age.
In March 2012 Channel 4 secured the rights to broadcast all UK horse racing events for the following year, including "crown jewel" events such as Royal Ascot and the Grand National, and the broadcaster saw it as an opportunity to freshen up its racing coverage and appeal to a wider audience.
Graham Fry, managing director of Sports Production Worldwide at IMG Sports Media Limited, prepared the company's bid to produce the programme.
Mr Fry said in his witness statement to the Central London Employment Tribunal: "John McCririck's presenting style was over-dramatic, liable to offend and would not have mainstream appeal."
Giving evidence to the tribunal yesterday, Mr Fry said he found McCririck's stints on reality shows "pretty disgusting and shocking, but as a broadcaster he had lost a lot of credibility".
McCririck, who alleges age discrimination, is taking Channel 4 and IMG to the tribunal.