You may have noticed we have two ‘runners in residence’ at the festival this year. But who exactly are they?

Des and Liz, who can be spotted throughout the festival brochure, have taken part in some pretty high profile sporting events in recent years. You may have encountered them carrying their homemade ‘Olympic torch’ on an epic run around Scotland in 2012. Or as unofficial ambassadors for the Commonwealth Games in 2014, when they were joined by neighbour/amateur documentary-maker Dick Snapper as they took their ‘People’s Baton’ across the country.

Now the trio are hitting the road again – this time to champion positive mental health on their ‘Take The Black Dog Out On A Walk Tour’.

Des, Liz and Dick are out and about in conjunction with Mischief La Bas, the much-loved Scottish street theatre company whose creations include the Timid Vikings (hell-bent on apologising for their ancestors’ wrong-doings), the Elvis Cleaning Company (who, as you might expect, combine singing Elvis songs with cleaning) and the Art Police (whose job is to make sure we don’t overdose on culture).

Dressed in Lycra sportswear and frequently talking nonsense, Des and Liz are clearly not intended to be treated too seriously – still, there is a serious point behind their appearance at a festival concerned with mental health.

In 2014 Ian Smith, co-founder of Mischief La Bas, took his own life after struggling with severe depression for several years. Ian’s illness was not something many people knew about, and his wife and company co-founder Angie Dight says the stigma around mental illness made her husband’s life even more difficult. “He wouldn’t admit to being as ill as he was,” she says. “He was embarrassed, he didn’t want people to know.”

Like this festival, Angie Dight believes that reducing stigma – and self-stigma - is an important part of helping people with depression, and Des and Liz’s latest adventure is, in part, an attempt to do this by raising the subject of depression in a way that is unthreatening and even fun. For their Take The Black Dog Out On A Walk Tour, Des and Liz will be engaging people in conversation about mental health – at festival events and out on the street – with jokes, questions and a lively curiosity.

The tour is also about Mischief La Bas carrying on its work with the same passion and enthusiasm that Ian, when he was well, was able to bring to it – as a tribute to Ian, and also as a celebration of life. “When a person dies their spirit lives on,” says Angie. “Their work lives on, everything about them lives on apart from their physical presence. We want to carry on the work, the joy.”

Des and Liz will begin their tour at our Moving Minds event at Kelvingrove Art Gallery and Museum in Glasgow this Saturday, World Mental Health Day. After that, look out for them at festival events and out on the street – and follow them on Twitter at @desandliz.