The UK's premier academic authority on terrorism, Paul Wilkinson, died on Friday. The Telegraph has (as usual in these matters) a rather good obituary.
Prof Wilkinson was head of the International Relations and Politics Department at Aberdeen when I was an undergraduate there in the 1980s. His profile was such that he was the first person the media went to when commenting on terrorism issues.
Which led to the student joke of the time - what's the difference between Paul Wilkinson and God? God is everywhere all the time. Paul Wilkinson is everywhere (except Aberdeen) all the time.