Let me suggest one possible logical explanation. GCHQ, by virtue of being a foreign entity can (and does) easily and routinely collect electronic communications information in the United States. The Brits can do this without having to worry about FISA courts, probable cause, etc. Want proof? Here is the NY Times piece on 17 March 2017 that cites one example:

One of Judge Napolitano's sources apparently was Larry Johnson. However, according to Johnson, the Judge did not accurately report what Johnson had said. According to Mr. Johnson , President Obama did not order anything. Instead, information collected by GCHQ was passed to people in the U.S. intelligence community and then distributed in an unauthorized manner. To deny that GCHQ did not do anything in response to a request from President Obama, but that does not mean that GCHQ (aka General Communication's Headquarters) was passive and doing nothing.

"We've made clear to the administration that these claims are ridiculous and they should be ignored and we've received assurances that these allegations will not be repeated," a Downing Street spokesman told reporters.

"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 the Department of Justice," said Napolitano. "He used GCHQ."

Andrew Napolitano, a political commentator and former New Jersey judge, said on Tuesday Obama used GCHQ in order to "make sure there were no American fingerprints."

I learned a long time ago that when you are close to the truth the opposition, if there is any, springs into action and launches a desperate counter attack. That appears to define what happened in the wake of Fox News suspending Judge Andrew Napolitano for the following claim :

The conspiracy theorizing also tested what is often called the special relationship between the United States and Britain. American intelligence agencies enjoy a closer collaboration with their British counterparts than any other in the world. GCHQ was the first agency to warn the United States government that Russia was hacking Democratic Party emails during the presidential campaign

Got that? US and UK have a "special relationship" and the GCHQ was THE FIRST (not the second or third) to warn Obama that Russia supposedly was hacking Democrat Party emails. When did they warn us? Before the discovery of the DNC hack or afterwards? If afterwards, how long? Who received that warning and what steps were taken to take counter measures? Lots of questions.

Here's another one--if the Brits knew that the Russians were hacking the DNC emails then how did they completely miss the Russians passing that info to one Julian Assange, who happens to be holed up in London in the Ecuadorian Embassy?

So why the enormous pushback from the Brits on Fox News? If we were playing Poker I would call that a tell. The Brits, normally implacable, allowed us to see their left eyebrow twitching. Judge Napolitano works for the Murdoch's, who also happen to have significant economic interests in Great Britain. I have heard the the British Government leaned hard on the Murdochs to do something about the Judge. So far, he has been suspended. Remains to be seen if he comes back on air.

To recap, we have the GCHQ routinely collecting on U.S. citizens and sharing that with the United States via NSA. Let me suggest one additional twist--the Brits decided, with encouragement from people in U.S. intelligence (John Brennan, perhaps? Mike Rogers?) to step up their collection on Donald Trump and associates and then passed that information, unfiltered and unmasked, to their U.S. counterparts. Is that what alarmed Devin Nunes earlier this week?

Let's stretch out a bit further. Is it possible that Britain's version of the CIA, MI-6, also got into the act and helped its former officer, one Mr. Steele, compile and distribute the now infamous dossier?

Why in the world would the Brits do something so risky? I think the answer to that is pretty simple, straight forward and self-evident. Trump’s policy positions on Syria and NATO represented direct threats to British interests. In Syria, Trump expressed a willingness to side with Russia in defeating ISIS and to withdraw the U.S. from the business of nation building. Trump also turned over the apple cart of status quo foreign policy by stating quite plainly that NATO was an anachronism and needed to be given a good, hard look. Anyone want to argue that our British cousins were comfortable with these policy shifts?

Therefore, it is not a train to crazy town to suggest that GCHQ and MI6 would be quite willing to lend a hand in helping take out Trump. Could that will be one of the key revelations coming down the pike in coming weeks. This also helps account for British establishments' consternation of the claims of Judge Napolitano. It also provides a plausible explanation for the tremendous pressure brought on Judge Napolitano who, without fully understanding what he was talking about, identified a the fat, ugly naked man in the room that looked a lot like the Queen (apologies to her Majesty).

Wouldn't that be a shocker--learning that the Government of Great Britain was working hand in glove with U.S. counterparts to sandbag Donald Trump and his Presidency?

Most overlook an obvious but obscure issue--GCHQ has been collecting intelligence on American citizens for years. Especially Americans of Irish descent or those with ties to Irishmen in the Northern Ireland. That was especially true twenty years ago. You do not have to hold Top Secret clearances to understand this fact. The British were collecting intelligence on Americans with names like Moynihan, O'Keefe, Lang and Kelly. Make no mistake about that.

One final point. The dog that did not bark. By that I mean that notwithstanding all of these machinations, no significant intelligence was generated that provided a smoking gun that could have spelled the end of Donald Trump. How do I know that? Only by deduction. If such information had been scooped up you can be assured that it would have found its way immediately to the front pages of the NY Times and the Washington Post. That has not happened. I think he real story is what did the Brits know and when did they know it? I suspect any further investigations into this matter will put a bit of a damper on US/UK relations.