The last person to be executed for treason against the United Kingdom was not actually British.
William Joyce was the ultimate radio shock-jock of World War II Britain. He was the voice and star of Nazi propaganda show Germany Calling, which was broadcast throughout the United Kingdom for the duration of the war. It was a very popular show: many of the British listeners wanted to hear what the “other side” were saying (their own media, of course would have been heavily censored) and the station also broadcast messages from British prisoners of war to their families.
And apparently it also played some jazz – but the story of the Nazi swing band will have to wait for another time.
Joyce was the most popular and prolific, and eventually the only, announcer on the show. In 1939 the announcers were dubbed “Lord Haw-Haw” because of their aristocratic-sounding accents and the name stuck – eventually it connected specifically to Joyce and he even adopted it himself. You can listen to his broadcasts on YouTube if you really must. I won’t be linking to them here; there’s too much Nazi propaganda around as it is.
Lord Haw-Haw’s final radio recording happened the day before Berlin fell. He was very drunk and his rambling embittered final speech was probably never broadcast. One month later he was caught by intelligence officers: they were suspicious, he went for his passport, they thought he was going for a gun and shot him in the ass. Beautiful.
Joyce went on trial in Britain for high treason. There was just one problem: he was not British. Although raised in Ireland and the United Kingdom, Lord Haw-Haw was born in Brooklyn, New York. He had a British passport – he misrepresented his nationality when applying for it before the war – but was not technically a British citizen.
So here was a tricky legal question: can you try someone for high treason against a country that’s not their own?
Britain really really wanted to find Lord Haw-Haw guilty, and eventually they did. They argued that because he had a British passport he was under the protection of the Crown, and therefore could commit treason against it. Pretty flimsy, but like I said, they really wanted him gone.
In 1946 Lord Haw-Haw was hanged, the final person in Britain to be killed on charges of treason. (The hangman got others, another war criminal the next day and murderers up until 1964, but no-one else for high treason.)