By Bob Chaundy
BBC News Profiles Unit
After the London bombings, the government is looking at whether so-called "preachers of hate" can be charged with treason. The last person to be executed for high treason, nearly 60 years ago, was the infamous Nazi propagandist Lord Haw-Haw.
From the beginning of World War II, an estimated third of the British nation used to tune in to Lord Haw-Haw's programme, Germany Calling, on the German equivalent of the BBC.
Listeners would be treated to such absurd doses of Nazi propaganda that it became a huge joke and, therefore, compulsive listening.
The presenter, William Joyce, was dubbed Lord Haw-Haw by a Fleet Street cartoonist. The name was taken from the sobriquet of the Polish-German playboy, Wolf Mittler.
Joyce became the stuff of comedians' humour - much parodied and ridiculed. Even advertisements used to send him up. But once German bombs began raining down on Britain's cities, the joke turned sour.
At the same time, Joyce's broadcasts became more sophisticated, cleverly mixing fact with the fiction.
With the BBC putting a time delay on certain news events for the sake of national morale, the listener often "heard it first" from Lord Haw-Haw.
When he was captured in 1945, Joyce was tried for high treason and executed. Even at the time, though, there was a doubt as to whether he could legally have been a traitor.
For Joyce was actually born in America of Irish parents. During the war in Germany - where he was granted citizenship - he could therefore claim to have alien status outside the British realm, thereby owing no allegiance to the Crown.
On the other hand, the Treason Act - framed in 1781 - does make provision for traitors who are citizens of "friends of the Crown", to which the US might well apply.
But what stymied Joyce was that after an upbringing in Ireland he had falsely claimed British nationality in 1933 in order to obtain a British passport.
As the historian AJP Taylor once noted, the penalty he was to pay for making a false statement on a passport application was not the statutory £2, but the hangman's noose.
Joyce came to England at the age of 15 and soon rose to become Oswald Mosley's deputy in the British Union of Fascists, though he was kicked out for being too anti-Semitic.
He seems to have struck up a relationship with MI5 after volunteering to spy against Republicans in Ireland.
Joyce's wife, Margaret, dominated him sexually
One of Joyce's biographers, Nigel Farndale, recently discovered documents showing that Joyce worked as an undercover agent for B5(b), a division of MI5, responsible for infiltrating extremist political groups.
Its head was Maxwell Knight, on whom Ian Fleming based his M character in his James Bond books.
According to Farndale, Knight tipped Joyce off that he was about to be interned and helped him escape to Berlin from where he was engaged by Nazi propaganda head, Josef Goebbels.
Farndale also maintains that Joyce's wife Margaret, who also broadcast Nazi propaganda from Germany and was a genuine British passport holder, owed her life to the relationship between her husband and Knight.
The couple had an extraordinary relationship, often tempestuous but, nevertheless, devoted. Both drank heavily, had affairs and she used opium. Her diaries reveal that Joyce was her sexual slave.
According to Farndale, though the evidence is largely circumstantial, Joyce agreed to remain silent about his MI5 links in return for sparing the life of his beloved wife.
Oswald Mosley: Joyce was thrown out of his party
The deal was done. He was hanged in Wandsworth Prison and she shipped abroad. She was later allowed to return to Britain where she died of alcoholism in 1972.
Several leader columns in British newspapers have suggested there is little to differentiate between the hatred expressed by certain extremist Muslim clerics and the Nazi propaganda that Lord Haw-Haw spewed out.
William Joyce always declared himself a patriot, wanting an alliance between Germany and Britain to counter the Communist threat. Then, so did Hitler.