ASK yourself what the most famous ship ever built on the River Clyde is and you could come up with numerous contenders such as the Cutty Sark, the Lusitania, and the three queens, Mary, Elizabeth and Elizabeth II, while naval people might suggest HMS Hood.

There is one ship which I would argue is the most famous Clyde-built vessel of them all because of its association with the UK monarchy – The Royal Yacht Britannia, which was launched 70 years ago today on April 16, 1953.

It is often forgotten that Britannia was very much a Scottish ship, built at the world-famous yard of John Brown & Co at Clydebank. It was awarded the contract to build the ship in February 1952, just two days before the death of King George VI who was the driving force behind the need for a new royal yacht.

The previous royal yacht, the Victoria and Albert, was obsolescent by 1939 and plans were made for a new yacht, but with the outbreak of war, the plans were quietly shelved. When the Admiralty revived the plan in 1951, King George was enthusiastic, not least because he could see it being used for his convalescence from the illness which eventually took his life – he never did get to board it, but from the start of her reign, Queen Elizabeth took a huge interest in the whole royal yacht project – indeed, it became known as Her Majesty’s Yacht.

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Well aware of the austerity that the British people were living through, she wanted the costs to be kept down as much as possible, but the yacht was still designed to be a floating palace, with staterooms and a dining room that could seat up to 200 guests, plus a small collapsible swimming pool and a portable stage, and a garage for a Rolls-Royce car if needed abroad.

From the outset, Britannia would have two roles – as the royal yacht in peacetime and as a hospital ship in the event of a war. That dual role dictated the design of Britannia, though her three masts were necessary because of royal protocol over the flying of flags. She would eventually displace more than 4000 tons.

Seven shipbuilding companies bid for the construction project, but John Brown won – largely because only it could deliver within the timescale wanted by the Admiralty. Britannia would eventually cost £2.2 million to build, and with John Brown’s world-renowned drawing office going full pelt, the keel was able to be laid down in June 1952.

The launch date was set for April 16 the following year and the Queen and Duke of Edinburgh made a day of it on Clydeside – their visit to Dumbarton Castle that morning attracted cheering crowds of thousands who watched as she received the keys of the castle from Major-General Alexander Telfer-Smollett, Lord Lieutenant of Dunbartonshire, who had won the Military Cross in the First World War.

The National:

Arriving at John Brown, with which the Queen was familiar as she had launched the Navy’s last battleship HMS Vanguard there in 1944 – the first ship she had ever launched – a huge crowd of shipyard workers and onlookers gathered.

Very few people knew the name of the ship until the queen stepped up and said: “I name this ship Britannia. I wish success to her and all who sail in her.”

Speaking to royal yacht officers and staff and officials of John Brown after the launch, the queen revealed how deeply personal this project was for her.

She said: “It has been a great pleasure to come to Clydebank today and once again to launch a ship in John Brown’s yard. This time it means more to me than ever before because the Britannia, which is now floating in the waters of the Clyde is not only the most modern addition to a long line of royal yachts which goes back to the reign of King Charles II, but she is to be at times the home of my husband and myself and of our family.

“I am sure that all of you who are present here realise how much the building of this ship meant to the late king, my father. He felt most strongly, as I do, that a yacht was a necessity and not a luxury for the head of our Great British Commonwealth, between whose countries the seas is no barrier but the natural and indestructible highway. With the wise advice of the Admiralty and of your firm, he laid the plans [for] a vessel which should wear the royal standard in days of peace and which, in the event of a war, should serve the cause of humanity as a hospital ship.”

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In November 1953, Britannia left John Brown’s to begin her sea trials. She passed, though not without tradesmen on board to complete “snagging” works. Now fully crewed with more than 200 officers and men – known as “yotties” – Britannia was commissioned into service on January 11, 1954.

Britannia’s maiden voyage took her from Portsmouth to Malta and the Queen and Prince Philip first sailed on HMY Britannia from Tobruk in 1954.

In her 44 years of service, Britannia sailed a total of 1,087,623 nautical miles. Her Majesty’s Yacht made more than 1000 official visits to various countries across the globe, including many Commonwealth nations.

She also played host to numerous high-profile events, including state banquets, diplomatic receptions and even royal honeymoons – Prince Charles and his first wife Diana famously spent part of their honeymoon on the Britannia.

But it was as a home from home for the Queen and the royal family that Britannia excelled. The Queen became very attached to the ship and shed a rare public tear when she attended the decommissioning ceremony in December 1997. The ship’s last voyage had included a visit to Glasgow, and as she sailed past Clydebank, her sirens were sounded in fond farewell to the town where she was born.

The Royal Yacht Britannia is now a five-star tourist attraction and museum at Leith.