Angus, in the newly created position of chief operating officer of Cossette UK, will oversee Miles Calcraft Briginshaw Duffy, Dare, Elvis, Spike, Brando, Band & Brown and Identica. He will also continue his role as the executive vice-president of the Cossette Group.
In the new role, he plans to boost collaboration across the agencies with existing clients and in new-business pitches.
Angus plans to split his time between Canada and the UK, but is considering a permanent move to London. He will continue to report to Claude Lessard, the chief executive and president of Cossette.
The appointment follows the promotion of Colin Schleining, the executive vice-president for Cossette West, to chief operating officer of the US operation.
Lessard said: "Gregor will be a real asset to Cossette in the UK. His calm and pragmatic management style is always valued."
Angus added: "London is probably our strongest mature market. The companies we've got here are youthful, sexy and hot brands that have so much potential."