The clue lies to your left as you enter Heath House Stables, the Newmarket training establishment of Sir Mark Prescott. Gleaming in the soft light of a summer’s evening is a two-storey building where there was once an old bicycle shed.

Fast approaching completion, the structure houses a plush new room for entertaining owners and plentiful office space. Doors are painted in the stable’s trademark livery. Pristine wooden decking along the top floor affords a panoramic view of the grounds inside Heath House, where Prescott will complete his 47th season at the end of the year.

There won’t be many more, although precisely how many remains to be seen. Prescott, 69, is adamant he won’t be rushed into retirement. He is grappling with the conundrum of departing too soon against lingering too long in the comfortable embrace of loyal patrons.

On the chosen day he will usher in William Butler, his assistant of 18 years who has known he will succeed Prescott for the last 16 of them.

It is one of the longest-serving apprenticeships in the sport. That new building serves to announce that the time is nigh. It will be Butler’s operations room, adjacent to the house in which Prescott will finally settle into that comfy armchair. But when?

When will I step away? It won’t be at the end of this season. It will be a very difficult decision but it’s time William got on

“I genuinely don’t know,” Prescott says. “It won’t be at the end of this season. It will be a very difficult decision but it’s time William got on. The first step was to get the new office built. The next step is probably not far away.”

He has no particular landmark in mind. His 65th birthday came and went. The transition might have happened early last year, when he had a tumour surgically removed from his back, but he rebounded with gusto from a setback that detained him for three months. And it’s unlikely to be as distant as 2020, when he will have been training for 50 years.

Those instances aside, a professionally appropriate moment may have governed his thoughts. Prescott believed he wasn’t far away from training his 2,000th winner on the Flat.

That might have made an apposite time to pass the parcel, yet the moment came and went.

Unbeknown to him, that milestone was reached, subject to verification, when Cartwright won an apprentices’ handicap at Pontefract on September 22 last year.

He landed something of a touch in the process. And so the wait goes on.

Learning to be patient

Butler, for his part, learnt the virtues of patience long ago. He arrived at Heath House in 1999 as a 21-year-old hell-bent on training but without the means to convert his dreams to reality.

More than two years later, when Prescott had seen enough of his assistant to suggest a handover, he may also have seen something of his young self in Butler and his aspirations.

Prescott came upon Heath House when Jack Waugh, to whom he was assistant trainer, retired in 1970. Waugh was old-school Newmarket: his father, Tom, trained Cinna to win the 1920 1,000 Guineas and his mother, Eleanor, was a daughter of the champion trainer Alfred Hayhoe.

By May of his final season, Waugh told Prescott he would be stepping down. The handover was completed before the end of the year, which made Prescott, 22, the youngest trainer in Newmarket by some distance.

“Nothing more was said until September, when Mr Waugh told me he’d had a word and all the owners bar one said they’d stay on,” Prescott reflects.

“He told me they would buy the yard for me, interest-free, and I’d have ten years to pay it back. William has a better bargain. It will take him longer [to own Heath House] but he gets a better deal in the end.”

Master and apprentice watch third lot return to Heath House

The process of integrating Butler into the business started in 2002. Prescott insisted Butler ran the proposal past a solicitor and knew that caveats would arise from it. He’d done the same thing himself back in 1970.

“I said to my stepfather, ‘This is the deal; what do you think?’” Prescott recalls of taking on Heath House. “He said I really ought to have something in writing, but he hadn’t met Mr Waugh.

“I told him Mr Waugh was the kind of man to whom you just say, ‘Thank you very much.’ And that was that.”

It must have been daunting for Butler, then 24, to take his solicitor’s concerns back to Prescott, whose occasionally irascible streak had not yet abated.

“The solicitor told me I was taking a lot on trust,” he relates, “and when I rang my father he said he’d never been involved with anything similar.

“He wasn’t sure if he could believe it; it sounded too good to be true.

“Anyway, I went back to Sir Mark,” Butler continues. “We got everything done and when I left the yard that evening it was one of the best nights of my life.

“The sales were on at Tattersalls and I remember vividly I was meant to meet a girl who was coming over from Ireland. I’d been angling to meet her for three years but I was so shell-shocked by the conversation [with Prescott] I didn’t even turn up.”

Another vivid memory for Butler was his interview for the job in October 1999. Prescott liked any candidate to ride out with the string; on this occasion Butler saw Alborada’s final gallop ahead of her second Champion Stakes triumph after the filly had missed most of the campaign.

“Sir Mark had been worried about her,” Butler reflects. “He changed the work around that morning so that Alborada led the gallop, and on the back of that she went and won.”

Prescott’s upbeat mood that morning did not do Butler’s prospects any harm. “She went with Farmost, who was the most wonderful lead horse,” he says.

“Farmost was a Listed winner and, unlike most lead horses who’d drop away when passed, he’d come back and win the gallop if the other one didn’t keep going.

“This was one of the most interesting gallops I’ve ever seen, because Alborada and Farmost repeated to the pound the gallop they did the previous year when Alborada won her first Champion Stakes.

“I then spoke to Miss [Kirsten] Rausing [who owned Alborada] and she said she didn’t want the filly to run unless she was going to win. I said I had no idea whether she would win but Farmost says she will. And she did.”

I couldn’t really face teaching another fellow from scratch and this fellow [Butler] seemed all right. My assistants have all been pretty good but I thought overall that William was probably the best of them

Jack Waugh died in September 1999, a few weeks before Butler started at Heath House. Prescott had been training for 29 years; perhaps Waugh’s passing sent him into reflective mode.

Either way, it wasn’t long before he decided to take Butler on permanently. It was previously his practice to take on a new assistant every two years.

“I suppose I couldn’t really face teaching another fellow from scratch and this fellow [Butler] seemed all right,” he says.

“My assistants have all been pretty good but I thought overall that William was probably the best of them. So I bet a very nice house on him – I bought it for him – and told him he could take over one day. I also told him if he didn’t want to stay, he could leave any time he liked.”

It was the last thing on Butler’s mind even if it flew in the face of advice his father, Michael, gave him in his youth. “My father worked 12-hour shifts: two weeks of nights and two weeks of days,” Butler relates.

Following a mentor

“He’d come home from work at eight in the morning and have breakfast with us, and he’d always say, ‘Whatever you do, don’t take on anything that makes your family life impossible. And here I am with two young children, getting up at half past four every morning…”

There are no regrets. “If I wanted to train I had to look for a job with a proven trainer,” he says. “I have been very lucky to have had Sir Mark as my mentor and over the years I have got to know the owners.

“He trains for the nicest people ever; that might not be a luxury I’ll be able to afford. And they pull my leg the whole time – especially Prince Faisal Salman [of Denford Stud]. He always rings up when Sir Mark is not around.”

William Butler will be able to entertain owners in a new facility that gives a superb view of the yard

The prince is not alone. Another long-standing patron is John Brown, the former Chairman of William Hill who knows better than most the value of information that might emanate from Heath House.

“Mr Brown tells me he has rung William when I am not here,” Prescott says. “He had bamboo under William’s fingernails for ten minutes and the only thing he got from him was that he thought he might have worked for me at some point.”

Prescott expects current patrons at Heath House to support Butler in the same way he was supported by Waugh’s owners back in 1970. Yet Butler harbours a concern.

“It’s not because the owners don’t like me or that I can’t train,” he says, “but because of their friendships with Sir Mark.

“Some will probably have run the course of having horses in training. I won’t have that huge financial pressure on other new trainers but there will be pressure and expectation to maintain what has been going on here for 50 years.”

Prescott accepts there will be alterations to the regimen at Heath House. He has rarely embraced the tenets of PR, much less the marketeers, yet change is already blowing gently through the place.

Say it sotto voce, but Heath House is on Twitter. A website is under construction for the first time.

Mr Waugh told me, ‘If you are conscientious a little bit of you will go down to the start with every runner you saddle. One day there will be nothing left’

“I’ve been brought along under Sir Mark’s thinking that if you train enough winners people come to you anyway,” Butler says.

“But to my mind there’s a little bit more to it these days. You see younger trainers using all manner of ways to promote their business. It makes a difference.”

All of that will be co-ordinated from the new office block. While Butler deals with hashtags and the like, Prescott will be close at hand but removed, by then reflecting on the sentiment bequeathed him on a grey November morning when Waugh came down to Heath House for the last time.

“It was drizzling down by the stone boxes,” Prescott reflects, “and Mr Waugh said, ‘I shan’t be back in now, I’ll leave it to you, I’m sure you’ll do well.’ And then he said, ‘Your owners will never understand, but if you are conscientious a little bit of you will go down to the start with every runner you saddle. One day there will be nothing left.’”

Only Prescott will know when that day dawns.

‘Day you start training is the last day off you ever have’

After 18 years and counting at Heath House, few new trainers will be as versed in the profession’s demands as William Butler. It is something he has yearned for since he rode ponies at his local riding school in Co Waterford.

Sir Mark and Butler with Melbourne Cup hope St Michel

“I spent every waking hour outside school with Harry de Bromhead [father of Henry],” Butler reflects. “That was an education. Harry loved anything that was free, including labour, and when the jumpers were out in summer he sent me to John Oxx for two years. They were the halcyon days of the Aga Khan.

“I had no racing background,” he continues. “My father was a barber and factory worker.

“He made his children sit A-levels, and when I finished that I did two years at Whitney College, went to Ian Balding’s and came to Heath House in October 1999.”

Butler’s early years were defined by Prescott’s well-earned reputation for kicking pupils and assistants into shape, although he maintains those are now distant memories.

“Sir Mark has changed very much,” he says. “He has passed on the hassle, so it’s me tearing my hair out these days, not him.

“I’m the one chasing the builders, the vet, the farrier, jockeys, while he stands back and laughs when I get wound up.”

Although Prescott concurs, he says Butler’s life will assume a new definition once the handover is complete.

“The nice thing for William is that he hasn’t yet had the ultimate responsibility,” he says, “but the day you start training is the last day off you ever have. Never again will that luxury be his. That is what William wants, of course. He will have it soon enough.”