The "Five Eyes" alliance (plus Israel) collaborate all the time...
"Three separate intelligence sources believe that former President Obama veered ‘outside the chain of command’ and employed British surveillance agents to conduct surveillance on Donald Trump’s team prior to the election, according to a legal analyst. "

"Judge Andrew Napolitano revealed on ‘Fox & Friends’ this morning that the sources spilled the details to him as the controversial case continues to dominate headlines."
“Three intelligence sources have informed Fox News that President Obama went outside the chain of command,” Napolitano said. “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.”

“He used GCHQ.” Napolitano explained.

... Plausible deniability indeed.