The Scotland chief is likely to be given the role of attack coach for the summer sojourn as Gatland plots a way to defeat the world champion Springboks in the three-Test series.
Townsend’s inclusion will inevitably raise hopes of a stronger Scottish presence in the squad than has been the case on recent tours. It is eight years, for example, since a Scot played for the Lions Test team and even that was a fleeting appearance, with Richie Gray seeing just 13 minutes of action as a replacement in the third and final Test against Australia in Sydney.
There is speculation that Gatland may also call on the services of Scotland’s defence coach Steve Tandy for the tour. Andy Farrell, the Ireland coach, had been expected to be given the defensive role but is believed to have opted instead for his country’s summer tour to the South Pacific.
The Lions are scheduled to play a Test match against Japan at BT Murrayfield on June 26 before leaving for South Africa where they will play five matches before the first Test against the Springboks in Johannesburg on July 24.
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Townsend’s absence means one of his assistants will take the reins for Scotland’s summer programme which has yet to be confirmed but could include matches against Japan, Georgia, Romania or Spain, with a development game against England also under consideration.