The former Gala and Border Reivers star is among a four-strong coaching team unveiled today, April 13, by head coach Warren Gatland.
Scotland head coach Townsend is joined by his assistant defence coach with the national side, Steve Tandy, plus Robin McBryde, assistant coach at Irish Pro14 club Leinster, and Neil Jenkins, kicking coach for the Welsh national side.
The Galashiels-born 47-year-old is joining Gatland’s staff at the second time of asking, having turned down the offer of a job on the Lions’ last tour, to New Zealand in 2017, as he’d only just taken over from Vern Cotter as the Scots’ head coach at the time.
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It’s not his first Lions trip, though, as Townsend, capped 82 times for Scotland between 1993 and 2003, represented the multinational team as a player in South Africa in 1997, overseen by fellow Borderer Jim Telfer and Ian McGeechan.
Accompanied by Kelso’s Alan Tait, Hawick’s Tony Stanger and Blainslie’s Doddie Weir, he played in six games, including two tests in Cape Town and Durban, helping the tourists to a 2-1 series victory over the then world champions.
“To be involved as a player and now as a coach is truly humbling,” said Townsend, with Gala as a senior from 1990 to 1995 and the Border Reivers, also based in Galashiels, from 2002 to 2004 and 2005 to 2007.
“The Springboks are a formidable opponent on home turf, but looking at the talent in England, Ireland, Scotland and Wales, it is a hugely exciting opportunity for us to do something special.
“One of the great challenges of a Lions tour is to bring together players from four different countries in a short space of time and create an attacking threat that will cause the opposition problems.
“It’s something I am already looking forward to.”
The tour will also give Townsend more first-hand experience of coming up against South Africa ahead of the Scots’ opening game of the 2023 Rugby World Cup in France and an autumn test match in Edinburgh in November this year.
Welshman Tandy, 41, said: “To take on the world champions in their own backyard is a massive test and one I am really looking forward to being part of.
“I am sure Gregor and I will benefit greatly from this experience and gain valuable knowledge about the Springboks ahead of the Rugby World Cup in two years’ time.”
New Zealander Gatland, 57, also head coach for 2017 and 2013’s Lions tours, added: “Gregor is doing an excellent job in charge of Scotland and is an outstanding coach.
"He also understands the challenges of touring South Africa as a player and what it takes to win there, so I am extremely happy he will be part of the set-up.
“As the tour approaches, we may look to bring in some extra resource, but this will be the core group for the time being.
“Touring South Africa is always a huge challenge, and clearly when the squad assembles in June to begin our preparations, everything is going to look and feel a bit different to previous tours, but having spoken to the coaches individually over the past few days, we’re absolutely determined to make it an enjoyable, memorable and ultimately successful experience for everyone involved.”
The squad for the tour in July and August, following a test match against Japan at Edinburgh’s Murrayfield Stadium on Saturday, June 26, is due to be announced early next month.