Danny Willett’s withdrawal from the British Masters was a blow for the tournament and thousands of golf fans at The Grove, who had expected to see the major winner in action.

The Masters champion had been due to tee off alongside eventual winner Alex Noren and Andrew ‘Beef’ Johnston at 12.35pm on Thursday of last week, but pulled out moments beforehand with a recurrence of a back problem. An unexpected opportunity had arisen for Justin Walters and John Glenn.

The South African professional had never met his emergency caddie until they were brought together only a couple of minutes before Walters struck his opening shot. But four days later they were able to reflect on a good tournament after the 35-year-old had finished in a tie for 33rd place on six-under-par, a result that secured his European Tour card for another year.

Walters had started Thursday as 21st reserve for the British Masters and, not expecting to be involved, was shopping in Tesco with his wife. Meanwhile, Glenn, who is a PGA instructor at the Chandler’s Cross resort and has previous tournament caddying experience, had been put on stand-by in case anyone dropped out.

Walters was first alerted to the possibility that he might play by his coach, Jamie Gough, following some withdrawals from the morning groups. But it was after contacting his agent, Ally Mellor, who had spoken to the European Tour, that the Johannesburg-born player found out he was first reserve for the afternoon, “but I just went up [to The Grove] to do some work with my coach really”.

Those plans rapidly changed when Willett pulled out.

Glenn had seen Mellor, who he knew, and was advised to get to the first tee, introduce himself to Walters and before he knew it was told to “get the bag”.

“I still didn’t really know if I was in or not because I hadn’t got a call from the tour, but my agent went into the tour office and he gave me thumbs up and I went on to the tee,” Walters said this week prior to competing at the Portugal Masters.

“No one really knew what was going on, not even the starter, and I hadn’t really played the course before; I played maybe four years ago off the front tees in a superball format. So I didn’t really know where to hit it.”

Glenn, who is from Rickmansworth and spoke to the Watford Observer on Saturday at the end of the third round, picked up the story: “So I’ve just got a three iron out… ‘just hit a nice one’. He pulled it a little bit but he made a good par and then he goes birdie, birdie.

“We get to the next hole and Alex Noren and Beefy have said ‘this could be a bit of a John Daly moment’, turning up at an event and maybe doing well because he started pretty good.”

Walters’ performance did not go on to scale the heights of the American’s unexpected PGA Championship triumph in 1991, but reflecting on that first morning he said: “It was quite a surreal experience. Three or four hours ago I was at Tesco shopping and I’m now in a marquee group at the British Masters walking down the fairway. It was a really odd experience but a lovely one at that.”

A level-par opening round of 71 was followed by a three-under 68 to see Walters safely make the cut. He followed that with a 67 and 72 to achieve his best result since finishing tied 11th at the Czech Masters in August.

His stand-in caddie, who achieved the highest marks for a male PGA graduate when he qualified in 2014 and has a “passion” for building relationships, said: “The first day was sort of tricky because I obviously didn’t know his game and then he started hitting a few shots and I’m like ‘God, this guy can hit it’. Then I’m starting to work out my course guide and yardages.

“But as the days have gone on, little and often, little and often and adding a bit each day and he’s then got more comfortable with me. I think I clicked with him quite soon and it was nice.”

Walters added: “It just kind of worked out. John was a lovely guy, he was very personable and a quiet, calm character to have with you in intense, crazy moments.”