Mr Rees added: 'The amount of freight has grown enormously over the last 25 years - most of it going by sea.

'The volume going by ferry now is phenomenal. It used to be a quarter of our business, now it's half, in spite of the recession.'

Mr Rees added that changing family sizes and travel patterns meant the number of passengers catered for on the new ferry remained the same as on the old - 2,000 - but with many more spaces for cars needed.

'When the Pride of Calais was built, cars going on board would have contained families of four or five, he said. 'Now it's much more often families of two or three, along with lots of single people and couples. It's vehicle space we need.'

While the Spirit of Britain, built in Finland, is a record for the Dover-Calais route, there are larger passenger ships on the seas, some notable cruise liners in particular.

But for the Continental route, the size of the ferry was limited not only by the size of the ports, but also by the need for the ship to be able to turn around within 45 minutes, unaided.

The largest ocean-going ships might take half a day to turn around, and need the assistance of tugs.