In order for GCHQ to carry out technical surveillance on Donald Trump it would have needed a warrant signed personally by the Secretary of State. Obtaining a warrant is governed by section 5 of the Intelligence Services Act 1994 (ISA). This provides, insofar as relevant, that in order to obtain a warrant the Foreign Secretary must personally think it is necessary for the action to be taken by the intelligence services, including GCHQ. This must relate to the carrying out of any function which falls within section 3(1)(a) of the ISA (and includes what is commonly referred to as “wire tapping”). It could theoretically include the interception of communications. In those circumstances sections 5 and 8(4) of the Regulation of Investigatory Powers Act 2000 (RIPA) would apply.

 A warrant – under either ISA or RIPA – could only be signed in the present context if it was in the interests of national security, having regard to the UK’s defence and foreign policies or in the interests of the economic well-being of the United Kingdom in relation to the actions or intentions of persons outside the British Islands. Is it possible that the activities of a lawfully nominated presidential candidate could reach this high threshold? This is so extremely unlikely that it is fanciful but even if it could be conceived, there are other difficulties.

The principal difficulty is what has become known as the Five Eyes Agreement. It has been suggested in some press reports that this is in fact the gateway used by the former President to facilitate surveillance of Trump. “Judicial analyst”, academic Andrew Napolitano and commentator for, amongst others, Fox News reported that:

“Three intelligence sources have informed Fox News that President Obama went outside the chain of command. He didn’t use the NSA. He didn’t use the CIA. He didn’t use the FBI, and he didn’t use Department of Justice. He used GCHQ. What the heck is GCHQ? That’s the initials for the British spying agency. They have 24/7 access to the NSA database. So by simply having two people go to them saying, ‘President Obama needs transcripts of conversations involving candidate Trump, conversations involving president-elect Trump,’ he’s able to get it, and there’s no American fingerprints on this”

There is an obvious flaw in this analysis, which is that it suggests GCHQ are accessing existing intelligence via the NSA database (i.e. material the US intelligence agencies already have on Trump). Such material would have “American fingerprints” all over it and would in any event need to be authorized. Under the Five Eyes agreement, President Obama wouldn’t have direct access to GCHQ – this is via secure liaison – but in any event the direction of traffic is going the wrong way. For this hypothesis to have any credence it would have to be the UK who identified Trump as a threat, obtained a warrant and then sought under the Five Eyes agreement express approval from the US authorities to get on with their surveillance activities. Quite apart from the absence of any legal basis existing (since the grounds could not objectively be made out) it would be diplomatically dynamite. Legal advice to the British Foreign Secretary – this would be routinely sought – would never have sanctioned such a course. The Prime Minister would have been briefed. Moreover, Napolitano’s theory that the former President managed to “leap-frog” his own intelligence apparatus is absurd. For his premise to work, US intelligence, far from not knowing anything about it, would have had to sanction it. If there were any truth in it, we would be facing a diplomatic incident of unparalleled seriousness. That does not appear to be the case. The greater risk to diplomacy is an attempt to prop up one fiction – that US spy agencies “tapped” Trump – by the invention of an even greater one, that British spy agencies did so.