Andrew Napolitano, a retired judge working for Fox News, declared this week that Barack Obama had bypassed US intelligence agencies and secretly colluded with GCHQ to wiretap Donald Trump.

Napolitano’s claims were risible and were viewed as such in security circles. There was amused musing on the intriguing scenarios being thrown up – did the President, unlike any of his predecessors, have his own hotline to the British intelligence services? Or did he arrive at Cheltenham, disguised in a fake beard perhaps, to make his request in person?

But then “Judge Nap” of tabloid TV is a colourful character. He is a believer in conspiracy theories about 9/11 and has a reputation for making statements not backed by any known facts, such as, for example, that Abraham Lincoln was secretly arming the slaves in the South before the Civil War.

Sean Spicer says Donald Trump did not mean Barack Obama personally wire-tapped him during campaign

The matter would have rested had it not been for White House spokesman Sean Spicer repeating the claim during his briefing. Both Republicans and Democrats in the Senate Intelligence Committee had dismissed Trump’s accusation, which began with a tweet in the early hours of the morning, that Obama had been eavesdropping on his calls, as had James Comey, the FBI director. But Spicer continued with the tale quoting Napolitano: “He [Obama] didn’t use the NSA, he didn’t use the CIA, he didn’t use the FBI and he didn’t use the Department of Justice. He used GCHQ.”

It is difficult to know whether it was Spicer’s own decision to try and use the Fox News story to try and shore up the rapidly dissolving allegations or whether he was acting under orders. It appears to be common knowledge in Washington that the hapless White House spokesman is frequently berated by Trump for his performances and told what to say in his briefings. The effect, however, was the same, the allegations were broadcast throughout the world.

GCHQ decided it cannot let this pass and must respond, an unusual move as British intelligence services do not normally make public statements. What followed was particularly robust. “Recent allegations made by media commentator Judge Andrew Napolitano about GCHQ being asked to conduct ‘wiretapping’ against the president-elect are nonsense. They are utterly ridiculous and should be ignored”, it said.

This is accusing Napolitano, who said he had three sources for his story, as peddling untruths. But the statement goes beyond him, aimed at Spicer and, by proxy, the White House. The Trump administration had a choice, either withdraw from backing the Fox News claim, or stick with it and effectively saying that British intelligence is involved in a cover-up with Obama in subverting US laws. Hours after the GCHQ response, the UK Government made clear that it had been assured by the White House that the allegations would not be repeated. However, Trump’s opponents are unlikely to let the matter rest. Susan Rice, Obama’s National Security Advisor was quick to tweet “the cost of falsely blaming our closest ally for something this consequential cannot be overstated.”

But beyond all this, it is actually the case that there is a British intelligence involvement in events which had been unfolding in America. GCHQ had been the first to alert its US counterpart, the NSA, about Russian hacking of the Democratic National Committee computers in the run up to the presidential elections: information gained from the hacks which were selectively released to help Trump’s campaign.