Etherington departed the Oswestry club last week following a disappointing start to the new season in which they remain winless in the North West Counties First Division South after eight defeats in 10 games.
To add to their woes, the Saints were humbled at their Park Hall home on Saturday, where visitors Hinckley AFC ran out stunning 18-0 winners in the FA Vase.
The scoreline was an all-time record margin in the competition.
St Martins director of football Steve Garnett said: “We are delighted to welcome Josh, a local manager with plenty of experience. He wanted to be a No.1 again despite enjoying his role as assistant at Haughmond this season.”
Gough’s St Martins head to Brocton in the league on Saturday.