Napolitano's "intel community" source for GCHQ spying claim was RWNJ Larry Johnson
Johnson was identified as one of Napolitano's sources by the NYT after he called the Times at Napolitano's request:
https://www.nytimes.com/2017/03/17/business/media/fox-andrew-napolitano-trump.html
Johnson's known for conspiracy theories
https://en.wikipedia.org/wiki/Larry_C._Johnson
including the falso 2008 claim that Michelle Obama had been videotaped using a slur against Caucasans (no tape or other evidence was ever produced, though later Johnson blamed the lack of evidence on intervention by the McCain campaign), and a falso 2013 accusation that John Kerry had admitted to war crimes, raping a Vietnames woman, in a Dick Cavett interview in 1971 (Johnson's fake evidence for that was altered audio of the interview that apparently showed Kerry saying things he hadn't said).
John Schindler's reminding his Twitter readers this morning that Johnson, whom he calls "Kremlin Larry," is a "flake and fabricator" who appears regularly on RT, Russia Today:
And Schindler remembers Johnson's NYT piece about there not being any real threat from political terrorism targeting the US, just two months before 9/11: