Iron Maiden’s Trooper ale has proved so successful that the makers are having to work overtime – before it’s even gone on sale.

But frontman Bruce Dickinson admits it wasn’t just a case of adding the band’s name to a bottle, and they actually had to audition for brewers Robinsons.

The award-winning firm tied in with Maiden to create a “secret squirrel” recipe. Interest has been so strong that they’ve moved to a six-day week to keep up with advance orders, with over 100 countries having expressed an interest in stocking it.

Brewery boss David Bremner tells the Sun that in their 175-year history they’ve never had to make three batches a day. “We haven’t spent a single penny on advertising,” he says. “This is history in the making for brewing.”

Maiden frontman Bruce Dickinson tells Heineken’s First Orders magazine: “We were asked if we’d like to create our own wine – the company said, ‘Motorhead have done it and it’s been hugely successful.’ I said, ‘Jolly good, but wine’s not really our thing. We’re more beer chaps.’

“We were really keen to get stuck into the brewing process and not just have our name plonked on the bottle. I was impressed with Robinsons because they didn’t instantly jump all over the idea. In fact, we ended up having to audition for them.

“We got together and did a blind tasting of about ten beers. We impressed them with our beer knowledge and we proceeded from there.”

Dickinson describes Trooper as “a great drink to have on a summer afternoon. It’s 4.8% so it’s got a bit of a kick, but it’s still a good session beer. I wanted to make sure it was subtle enough so you could enjoy it for a while.”

More than 250,000 pints of Trooper have been ordered in advance of its launch on May 9.