The line, which recently launched Breakaway (pictured) and Getaway, will add another four new ships between 2015 and 2020.

Francis Riley, director of international markets, said: “We need to be looking at the long-term strategic investment in international markets; whether that’s through marketing, buying more charter seats, or how we’re driving more distribution.”

He said getting more agents selling Norwegian, and more training and education to make sure they are targeting the right customers, was key.

“The biggest opportunity for us is to support the capacity growth that’s coming in with all our new ships by developing our international business – and that bodes really well for the UK as it’s our biggest single market outside the US.”

Riley added: “I think my biggest fear is that typically, there’s only one cruise specialist in any agency. That keeps me up at night.

“Every agent sells a package but not every agent feels comfortable selling a cruise, and that has to be my biggest concern as the sector grows. It’s our responsibility as an industry to tackle this issue.”

He said he understood agents had a lot of pressures so said it was “important to make them understand the differentiation between the cruise brands”.

Riley claimed Norwegian’s Partners First scheme was enjoying huge success by rewarding agents that work in true partnership with the line to grow both their businesses.

He claimed that despite reducing base commission to 10%, Norwegian had paid out “just as much if not more” in rewards to those key agents that had performed really well for the line.

“Agents have the opportunity to earn well in excess of the base rate and many do. Many of them are retaining more commission than they ever have done with us,” he said.

Riley claimed Norwegian, having posted 24 quarters of consecutive growth, could now truly claim to be “industry leading rather than industry following”.

“By any measure, whether it’s EBITDA, net per share, net revenue, Norwegian is now best in class,” he said.