Little wonder, then, that he feels he has nothing to prove.
The big winger’s story is well told but has added piquancy as he prepares to make his Lions Test debut against the Springboks in Cape Town.
A former South Africa Under-20 international, he was part of the Baby Boks squad which reached the final of the 2014 Junior World Championship. The side was captained by Handre Pollard and van der Merwe appeared as a second-half substitute as they lost a closely fought final to England.
The two men’s careers have since diverged. Pollard established himself as South Africa’s first-choice fly-half, anchoring the side to the 2019 Rugby World Cup triumph and scoring 22 of their 32 points as they defeated England in the final.
Van der Merwe, unwanted by the Boks, headed for Europe and an injury-blighted spell with Montpellier before finding a home from home in Edinburgh, fulfilling the residency requirement and playing for Scotland.
The pair will be on opposite sides on Saturday as Pollard wins his 50th cap.
The adopted Scot has taken the scenic route but he finally has the chance to play Test rugby in the country of his birth. Warren Gatland, the Lions head coach, has warned him to expect “verbals” but van der Merwe seems blissfully insulated against any bad vibes.
“My family and my mates are buzzing for me,” he said. “A lot of them are probably going to support the Springboks but they’ve also said that whenever I get the ball in hand they will support me. There are a couple of jokes here and there, saying ‘don’t score too many tries against us!’”
He is adamant there is no rancour on his part about being overlooked by South Africa.
“I feel I have nothing to prove to them,” he said. “I came over and played for Scotland and now the British and Irish Lions so I’m just going to go out there and show what I can do.
“It has been six years and I don’t have any sour grapes or anything like that. So, it is not about going out there and trying to show them that they should have kept me – I’m happy with how everything went with my move.”
He will be up against Cheslin Kolbe on his Lions Test debut and could hardly have wished for a tougher opponent. Ronan O’Gara described the Boks winger as the “Lionel Messi of rugby” and van der Merwe is acutely aware of his opponent’s pace and trickery but he intends to give as good as he gets.
“He’s a world class player,” said the former Edinburgh man. “His ability to beat boys one-on-one is amazing so it is just about staying on top of him and not giving him any time on the ball, and when I have my shot at him then he needs to defend me as well.”
Gatland thinks South Africa will target van der Merwe but the hosts issued a strong rebuttal on Friday. “We’ve never been that kind of team and will never be that kind of team,” insisted Siya Kolisi, the Springboks captain.
Nevertheless, van der Merwe is not so naive as to think his unique status won’t be commented upon by opponents seeking any sort of edge.
“In any game you play you always get some verbal abuse and you get people getting stuck into you,” he said. “I’m used to it. I know I’m going to get a few boys holding on to me, pushing me here and there but I’m just going to avoid it and focus on my game.”
Van der Merwe, who will play for Worcester next season, expects an aerial bombardment but has warned that he will punish inaccuracy with the ruthless finishing power that has already rewarded him with five Lions tries.
“We know there are a lot of high balls coming on Saturday,” he said. “They love the kicking game. But obviously if those kicks go too long and I have the time on the ball to run back at them then that’s what I enjoy, so it can go two ways. Their kicks will have to be on the money.”
There has been plenty of confident talk in the Lions camp this week, with Gatland leading the way. Although the tourists were edged 17-13 by a South Africa A side last week, the Lions says they have drawn great confidence from their performance at the scrum and maul, which are pillars of the Springboks’ game.
Despite the defeat, Gatland claimed they had “dented the ego” of the world champions and it is a theme forwards coach Robin McBryde was happy to expand on.
“Physicality is an area of the game the Springboks pride themselves on. I’m sure they’ll be frustrated after the A game when they didn’t get any advantage from a mauling point of view and didn’t get anything out of the scrums,” McBryde said.
“We’ve got to step things up and build on that performance. We want to scrummage. We feel that technically we’re very good. We’ve been great to date.
“But I expect them to come a lot harder again in the same areas. If anything, that’ll make them a bit hungrier again. They’ll rise to the challenge again. We need to step that up and make sure we don’t rest on our laurels.”