If you have any doubt that the Brits, i.e., GCHQ, along with Australia, Canada and New Zealand are/were conducting electronic surveillance in the United States (and the United States, i.e., NSA, conducting electronic surveillance on all of them) Google “Project Echelon” and “FIVE EYES”...
The EVIDENCE that the Trump campaign and Trump’s associates were the targets of electronic surveillance is the very existence of a transcript of the conversation between Mike Flynn and Amb. Kislyak; there’s no other way to obtain that transcript. It’s entirely possible that the Brits did not provide the transcript of Mike Flynn’s conversation with Amb. Kislyak. It could have been New Zealand, Canada or Australia. Of course, it’s equally possible that it was a “rogue” (Read: Loyal to Obama) element of the US Intelligence Community or a law enforcement agency with the capability to intercept communications.
ManHunter is correct. Obama used ECHELON to get the surveillance done. That is why there's not going to be any paper or digital "evidence" found.
It's also why all mention of this has been scrubbed from the MSM; the five participating nations cannot allow their populaces to become aware of this mechanism they've devised to circumvent their much-touted "civil protection" laws against domestic spying on their own citizens.
Napolitano will be lucky if the only consequences he suffers is being given a temporary time-out. And, unless Trump finds a living, breathing whistleblower witness willing to testify, he's going to be falsely impeached by fabricated "evidence".