He is only the second elder in modern times to be elected to the Church of Scotland’s highest office.
But with a shrinking number of ministers, he suggested the church was having to rely more and more on elders.
In a BBC radio interview, Lord Wallace said: “Increasingly many responsibilities are falling on the shoulders of the elders. Kirk sessions are full of people who have had such a wide range of experience. I think the church should be tapping more into that reservoir of expertise, of experiences.”
The first elder to serve as Moderator was also the first woman in the post, Dr Alison Elliot from Edinburgh’s Greyfriars Kirk, who had the role in 2004-05.
Lord Wallace said he hoped his election would be an encouragement to elders. “It’s 17 years since Alison was Moderator – I hope it's not another 17 years until another elder is Moderator because I think the eldership has so much to contribute.”
Lord Wallace, who was Deputy First Minister from 1999 until 2005 and later Advocate General in the UK government, 2010-15, is an elder at St Magnus Cathedral in Orkney. At his installation as Moderator on Saturday he wore a robe lent to him by former Liberal leader and Holyrood presiding officer Lord (David) Steel, which belonged to his father the Very Rev Dr David Steel who was Moderator in 1974-75.