Founded six years ago by Peter Stocks and Lynda Richards-Stocks, Viking Splash Tours has transported 70,000 tourists a year on the capital's road and waterways. In keeping with the Viking theme, passengers were encouraged to terrify the locals with their screams.

"While it has always been our intention to sell the company at this point and move on to other ventures, it is still somewhat emotional to hand over your baby to someone else, " said Richards-Stocks. "We are very pleased with the sale and believe Sea Safari to be a good fit."

The amphibious landing craft, rumoured to have seen service on D-day, have been upgraded to meet modern emission standards.

But they will nevertheless make a curious addition to eco-conscious Sea Safari.