Hannigan was in US in March 2016:
7 March 2016: GCHQ: Director Robert Hannigan dispels myths about encryption in MIT speech
In a speech entitled “Front doors and strong locks: encryption, privacy and intelligence-gathering in the digital era” Director GCHQ shares his thoughts about this pivotal topic with an influential audience at the Massachusetts Institute of Technology
https://www.gchq.gov.uk/news-article/director-robert-hannigan-dispels-myths-about-encryption-mit-speech
Bletchley Park: Robert Hannigan CMG
Robert is ... one of the few non-US citizens to be awarded the US Intelligence Distinguished Public Service Medal.
Wikipedia: National Intelligence Distinguished Public Service Medal
The Director of National Intelligence (DNI) established the award on October 1, 2008 to acknowledge individuals who rendered extraordinary service at considerable personal sacrifice and who were motivated by patriotism, good citizenship or a sense of public responsibility.
Recipients:
Mr. Robert Hannigan (2017)
https://en.wikipedia.org/wiki/National_Intelligence_Distinguished_Public_Service_Medal#cite_note-3