It’s one of London’s urban legends that an American entrepreneur once thought he was buying Tower Bridge, but purchased London Bridge instead.

Contrary to popular belief, the grandson of Robert McCulloch has now reiterated the truth to BBC London, and insisted the rumour was “not true at all”.

In 1968, his grandfather bought the original Victorian London Bridge and reconstructed its exterior blocks in Lake Havasu in Arizona.

“My grandfather knew exactly what he was buying,” said Michael McCulloch.

“But the stories kept coming up and kept providing free press and encouraging people to visit Lake Havasu and the bridge, so he never corrected it,” he explained.

According to the website for neighbouring Tower Bridge, the alternative version of what happened became a “popular rumour”, but was “vehemently denied” both by Robert McCulloch and by Ivan Luckin from the City’s Common Council, who arranged the sale.

Nevertheless, the old London Bridge made it to a fledgling desert city Robert started building after spotting Lake Havasu itself on the otherwise barren landscape.

Those who lived there, where there was just one school and a grocery store, said the news of the bridge coming to the desert led to a drastic increase in the population.

An entry on the Tower Bridge website said following the sale, each of London Bridge’s 10,276 exterior granite blocks were numbered and then shipped to the US.

In 1973, Queen Elizabeth II officially opened the new London bridge.

On Thursday, Michael visited the new London Bridge which replaced the one his grandfather bought, and saw the structure that spawned a decades-long myth.

“The story and the bridge have played a huge role in my life and the life of my family and being in London standing on the bridge, I feel very proud,” he said.

“I feel a real connection with the place and whenever anyone asks me my favourite city, I always say London.”

The visit, organised by London Bridge’s owner City Bridge Foundation, gave Michael – a proud Freeman of the City since 2015 – the chance to once and for all kill off the old story that his grandfather thought he was buying Tower Bridge.

“It is something that keeps coming back – maybe it’s because the British feel they were duped into giving up a treasured item and the story makes them feel like they didn’t give up that much after all,” he joked.

The trip was also made by the mayor of Lake Havasu City, Cal Sheehy, who was in London to receive his own Freedom of the City of London by the City of London Corporation.

After the city was created in the desert from nothing by Robert McCulloch, Sheehy says the bridge played a crucial role in its development as a place to live. He added it was also Arizona’s second biggest tourist attraction.

Giles Shilson, City Bridge Foundation’s chairman, said: “We were thrilled to be able to show Michael the bridge that replaced the one his grandfather bought, to give him the chance to set the record straight once and for all, and to strengthen our long-standing links with the mayor and Lake Havasu City.”

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