Bob Robertson and Linda Cullen had a half-hour radio comedy show on CBC Radio One that they expanded to an annual New Year's Eve CBC TV special. They have also had a half-hour weekly comedy show on The Comedy Network and CTV.
While Linda's repertoire of "voices" has been limited, partly due to a small number of female public figures worth impersonating, Bob has gone to amazing heights of mimicry in the voices of the Prime Minister, the President of the United States and many others.
If he called you on the phone saying he was the Prime Minister of Canada, I challenge you to tell him from the real thing! Tip: Wait for the joke.