Mayall's character, William Charles Bedford, is a Bombardier in the King's Royal Bedfordshires, and is portrayed by a TV ad as a 'dashing hero' leading the English in a historical battle.
The six-week TV activity is complemented by social media content on YouTube, Facebook and Twitter, and in-pub and in-store activation.
Chris Lewis, marketing director at Wells & Young’s, said: "Marketing in the ale category needs a creative shake up. There are too many woolly jumpers and cosy corners that patronise our drinkers.
"Creating The Bombardier, and bringing in Rik Mayall to play him, is our way of adding some much needed creative flair and humour to ale advertising.
"The Bombardier is a dashing hero, revered by his men and loved by everyone who meets him. He's the epitome of great character and taste and just like our beer, it's Bang On for our target market."
The campaign was created by Karmarama with PR by Kaper and media planning and buying handled by ZenithOptimedia.