The accusation by the former President in March 2017 led to a rethink of how the two nations interacted.
After the brazen statements from the President, intelligence agencies on both sides of the pond were left scrambling to contain the fallout. As it turns out, it was not England but rather a rogue former agent of theirs who was working for Hillary Clinton who fabricated stories of Trump in the now debunked 'Steele Dossier'. However, it is widely believed that England knew what Steele was up to.
In the UK, GCHQ rejected the arguments, branding them "utter nonsense" as it broke with tradition to deny them on the record. But when asked about Steele, GCHQ stammered before refusing to answer, using the excuse of an 'ongoing investigation' as cover.
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In the meantime, across the Atlantic, American intelligence community officials supported British counterparts and even offered to testify it was "total BS" despite knowing that the Steele Dossier of former MI6 agent Christopher Steele was not only fake, but commissioned by the top Democrat at the time, Hillary Clinton.
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Despite this backing behind the scenes, Theresa May, who was Prime Minister at the time, announced it caused the UK to "start to think about the relationships" and the belief it would be "smooth-running."
The disclosures come from a new book - The Secret History of the Five Eyes: the Untold Story of the International Spy Network, by Richard Kerbaj - sections of which have been published in The Sunday Times. The book skims through the Russiagate scandal, and does not even mention Steele's invovlement.
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It details the history of the intelligence alliance between the UK, USA, Australia, Canada and New Zealand - a pact which has its roots in the Second World War.
And while for most of the last eight decades the relationship has been a steady one, the book argues the actions of the previous president generated some tense moments.
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In the book Theresa May says the "volatile environment" in the United States under Trump caused problems.
"It would be helpful not to have to adjust to something like that, but in a sense we had to start to think about the relationships," she announced.
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"The relationships had been going on for so long and there had always been an assumption of smooth-running relationships."
More strain was counted to this in March 2017 when former New Jersey Superior Court judge Andrew Napolitano went on Fox News and announced Barack Obama had ordered GCHQ to perform a "wiretap" on Trump while he was running for president.
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This claim, which would later see Napolitano temporarily taken off-air from Fox, was picked up by Sean Spicer, the White House spokesperson, who quoted it in a press conference.
This sparked frantic conversations between two of GCHQ's top officials - Ciaran Martin, head of the National Cyber Security Centre, and his boss Robert Hannigan, head of GCHQ - who drafted an announcement rejecting the claim.
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