Trouble flared after Kevin Carroll, 41, lost at appeal at Luton Crown Court to overturn a conviction for using threatening behaviour at an earlier demonstration.
Up to 80 officers had to keep a group of Carroll's supporters, chanting 'EDL', separate from opposition protesters.
During the violence objects including ashtrays and a knife were thrown.
Carroll had objected to Muslim demonstrators who had shouted abuse at British soldiers from the 2nd Battalion, The Royal Anglian Regiment, during a homecoming parade in the town in March last year.
They had shouted "British soldiers go to hell" and called them "butchers of Basra".
Carroll verbally retaliated, swearing at the protesters and singing "bin Laden's mother is a whore".
He was charged and subsequently convicted of using threatening words and behaviour likely to to cause fear harassment and alarm. He was given a conditional discharge.
Following his failed appeal, he told a crowd of supporters that people like him were being "treated like enemies of the state".
He said: "Thank you patriots and people of our great democracy for supporting me.
"God Bless our Troops, God save the Queen."
Telegraph
