"They were dependent on fate and the tides. But everyone was in the same boat. You needed to be quick-witted and make new friends quickly."

Dr Milne says: "There was a lack of a clocking-on industry which gives the population a sense of living in their own time. Contrast that with the Manchester textile industry with its high percentage of male workforce behind closed doors with weekly wages in stable jobs."

Former sailors Terry Southers, Victor Chinn, Gary Shaw and Gerry Fitzpatrick were proud to have grown up seeing the world, and regretted this chance was denied to today’s generation. The sheer toughness of earlier Liverpudlians is explained by maritime historian Patrick Moran, who says: "Pilots would row to the southern Irish coast to wait for in-bound Liverpool ships."

A couple of interviewees went to sea to avoid problems at home and bad social influences. They agreed the experience matured and straightened them out.

Prof Rediker says: "The origins of the phrase ‘motley crew’ began with Liverpool ships who were crewed by men of all nations. They brought this home and it made for a very different city.

"The city has a long tradition of maritime radicalism and there were pitched battles against the press gangs here and accounts for the population’s anti-authoritarian attitude."

While the city has partly changed beyond recognition, John Curry, who is chairman of Liverpool Pilots, puts this in perspective.

"We have the same problems on the river as King John did with his longships. The prevailing westerly winds come across the Atlantic, causing swell and high seas," says John.

"We can combat the conditions better than King John’s sailors, but the end result is winter weather which makes Liverpool untenable."

However, there is no place in this film for the Vesteys, Rathbones, McIvers, Holts, Tates, Levers and other merchant princes who powered Liverpool through its golden age.

"That was quite deliberate, as we wanted to show the kind of ordinary people who built Liverpool with their own sweat," says Roger.

"There is much that I enjoyed in the making of this film, but the final memorable moment was after we’d sent copies out to contacts.

"I was mowing the lawn at home and my mobile phone rang, and I was staggered when I heard who it was."

It was former Labour minister Tony Benn, who told Roger that the film was "absolutely fantastic" and gave him "a deep understanding of Liverpool."

But then, as the film says, Liverpudlians have had a disproportionate influence on the psyche of the planet.

* COPIES of the Passport to Liverpool DVD are available from www.merseyshop.com at a price of £11.99, plus £2.50 postage and packaging.