The Bloody Caesar was invented 40 years ago by a Calgary bartender. (CBC)

Little known outside of Canada, the Bloody Caesar is celebrating its 40th anniversary as a campaign kicks off to declare the uniquely spicy and savoury drink the country's national cocktail.

Red and white balloons filled the lobby of Calgary's Westin Hotel on Wednesday, where the drink was first invented in 1969. Mayor Dave Bronconnier, other dignitaries and family of the cocktail's creator mingled and tasted variations of the drink originally created with vodka.

Bartender Walter Chell was asked to create a signature drink to celebrate the opening of a new Italian restaurant in the Calgary Inn, which is now the Westin.

"He's Italian and a fantastic cook and came up with a concoction of mixing clam juice, with tomato juice and Worcestershire sauce, Tabasco and vodka and because of his Italian ancestry, decided to call it Caesar," recalled granddaughter Sheena Parker.

"There was a British man at the bar at the time and he said, 'That's a bloody good Caesar', and that's where he came up with the Bloody Caesar."

Mott's Inc. started producing Clamato juice later in 1969.

Walter Chell's granddaughter said he would be humble about his role as the inventor of the beloved Bloody Caesar. (Family photo)

Chell died in 1997 but his classic Caesar recipe has become a staple of just about every bar in Canada, with more than 350 million Caesars quaffed every year, according to Mott's.

"My grandfather was a very humble man and he would have been like, 'Oh, it's nothing, what are they talking about?'," said Parker.

Mott's has started an online petition to declare the Bloody Caesar Canada's national cocktail.

"We're hopefully going to take this right to Parliament Hill and see if we can actually get it acknowledged," said the company's vice-president Andy Bayfield. "We want to see it get recognized and in its place among those truly intrinsic Canadian things."

Most attempts to order a Bloody Caesar outside of Canada are answered with blank stares or an attempt to steer one toward a Bloody Mary, which is made with tomato juice.

With files from The Canadian Press