It is just a few months since Pitman revealed that she had successfully fought off cancer, but she said that the illness had not influenced her decision. "I am happy to say that it is nothing to do with my health," she said. "I am not ill, but this seems the right time for Mark to take over. I'm not really retiring, but I won't be playing centre forward any more. I shall be on the subs' bench. I've hardly been anywhere outside this country apart from Ireland and Spain and Italy. I would love to see the big races in Australia and the United States and Dubai.''
Cheltenham has featured prominently in Pitman's 24-year training career, most famously when she became the first - and so far only - woman to train a Gold Cup winner with the success of Burrough Hill Lad in 1984. Seven years later, Garrison Savannah won the same race, with her son in the saddle, but the following season Pitman was the focus of less flattering publicity.
She was accused of running Golden Freeze, a 150-1 no-hoper, in the Gold Cup simply to upset the hot favourite, Carvill's Hill, and thereby increase the chance of her other runner, Toby Tobias. She was cleared of any malpractice at a Jockey Club inquiry, but among the thousands of punters who backed Carvill's Hill, the memory can still raise hackles.
"I wanted to make the announcement here at Cheltenham because of the wonderful warmth everyone here has shown to me over the years," Mrs Pitman said yesterday. "I have so many marvellous memories of Cheltenham. It would be very nice if I could go out with a winner at my final Festival as a professional trainer, but it wouldn't be the end of the world if I didn't.''
For a few strides after the last fence in the William Hill National Hunt Chase, it seemed that Nahthen Lad had read the script, but he could not find a final effort to take him past Betty's Boy and Island Chief, and finished only third. But Mrs Pitman does have a runner, Ginger Fox, in the County Hurdle on Thursday - the last race of the meeting. It will be a popular choice with punters.
There will be a tearful parting from Aintree too next month. Pitman trained two Grand National winners, Corbiere (1983) and Royal Athlete (1995), and also saddled Esha Ness, who passed the post first in the void National of 1993. She is also one of only two trainers to have a complete set of Nationals, in England, Scotland, Wales and Ireland.
Mark Pitman was his mother's assistant until setting up as a trainer in his own right in 1997. He plans to train about 80 horses at Weathercock House, including 35 recruits from his current yard.
"Mother has been one of the best-known people in the game," he said. "She transcends racing and is known by every man and woman in the street. She has always been straight and told the truth and those are her ideals. I hope I'll be able to uphold them. I am going to be the captain of a very big ship and we won't be looking to be just among the best in Lambourn. We want to be among the best three stables in the country.''
After pausing to compose himself, he added: "I shall give it my best shot and carry on the way mother wants me to. This is the end of an era. I have ridden for mother, been her assistant trainer and we have been closely involved for a long time. If a door doesn't open she will try and open it politely. But if it still doesn't open she'll kick it down.''
The sturdiest door which Pitman pushed against was the one which insisted that training racehorses was a man's job. It was, inevitably, no match for her, and the many successful female trainers in Britain today are in her debt.