Barclay, who continues to play for Edinburgh after retiring from national duty earlier this month, has 76 international caps and has represented Scotland at three world cups.
Described as a “natural leader”, Barclay will share what he has learned off the pitch, with a focus on topics such as transforming toxic team cultures, the challenge of implementing change, the importance of strong leadership and overcoming adversity.
His appointment adds to the agency’s high-profile roster, which includes adventurer Mollie Hughes, who is currently bidding to become the youngest woman to ski solo to the South Pole; plastic pollution campaigner and world-record stand-up paddle-boarder Cal Major; and Olympic horse rider Jonty Evans.
Barclay said: “Playing rugby is hugely demanding physically, but as my career has progressed I’ve learned a huge amount about how success is shaped by what happens away from the pitch.
“My experience in the rugby world has shown me the critical importance of establishing strong leadership, values and a positive team culture that allows people to work more effectively together. I’ve seen first-hand how changing team culture and implementing new standards can have a massive positive impact on performance and results.”
Speaker Buzz founder Debbie Byers added: “John is known in the rugby world as a brave, intelligent and respected leader and I’m very excited and proud to have him join the Speaker Buzz team. I know his inspiring story and his experiences will have a huge positive impact on those who hear his talks.”