Too many years ago I worked alongside a quiet li'l man who married a Jewish lass in 1947 while he was serving as a Warrant Officer with the Royal Horse Artillery in what was then the British Mandate of Palestine. He remained a British citizen but whatever he'd got up to during the War of Independence following the establishment of the state of Israel in 1948 had made him a 'Friend of Israel', which opened up some unusual opportunities for him.
One of those opportunities was serving as an unpaid Air Marshal for El Al: he'd contact the airline whenever he wanted to fly abroad, they'd issue him with his instructions as he arrived early at the airport and he then joined the passengers as they boarded, sat down in a seat at the rear of the cabin and kept his eyes open for any trouble. He never carried a gun, relying on keen observation and his unarmed-combat skills to deal with anyone who might threaten the safety of the aircraft. He told me the worst bother he ever had to deal with was the odd drunk (there were other Israeli Marshals aboard with weapons who were briefed to combat anything more serious) and he'd travelled for free ever since the early days of the airline.
It took me a long time to gain his confidence before he told me about his cheap-travel arrangements - and many details of his history he never revealed to me at all. I wouldn't have written this if he hadn't died a few years ago.
Here's to all those who put the safety of others before their own.