An advert for UK plc that was always the hottest ticket in town

Mandela or carried the leaders of the free world to Normandy for the 50th anniversary of D-Day it elevated important moments to spectacular, historic occasions.

The yacht was a statement as well as a floating embassy-cum-trade platform. Like her most famous passenger, Britannia was dependable, instantly recognisable and stylish without being ostentatious.

There was not a gold tap in sight. Her drawing room had the feel of a country vicarage rather than a palace.

Yet even if she sailed into a port heaving with cruise liners, it was the Glasgow-built ex-hospital ship which always drew the crowds. But, in the end, it was not old age which did for her but the politicians. And it is the politicians who remain the biggest stumbling block to any replacement.

In 1994, it was clear that she would soon need a complete refit at a time when both the Monarchy and the Tory government were going through a bad patch. So, John Major announced that she would be decommissioned in 1997, while making no firm decision on a replacement.

Shortly before the 1997 election, however, the Tories decided to make a new royal yacht a manifesto pledge. In doing so, they neglected to secure the agreement of a resurgent Opposition who were only too happy to make it an election issue.

When Tony Blair’s New Labour won by a landslide, the yacht was doomed. A tearful Queen joined the rest of the Royal Family at Portsmouth to say farewell. Here was a ship she had launched, named, helped design and in which her young family had some of their happiest moments.

More than a decade later, when I asked Mr Blair about that episode, he had a confession: ‘After we’d agreed to get rid of it, I actually went on it and I remember thinking, “That was such a mistake to have done that.”’ But any new yacht would, first of all, need the support of the public and main political parties – and it is inconceivable the present Labour leadership would concur.

Crucially, it would also need the support of the Royal Family and that should not be taken for granted either. The Queen will not have forgotten the way that she and her yacht became a political football.

Even if it were built with private funds, there would be many major hurdles – even the word ‘yacht’, with its connotations of idle pleasure. The irony is that a new yacht could be a huge asset for post-Brexit Britain. But it would also require a passionate and determined political champion as well as a very skilled financial one.

It’s a great idea, Boris – one for which this paper has campaigned keenly in recent years. But don’t hold your breath.