Legitimate and peaceful protesting is part of being a free society; there wasn't any legitimate and peaceful protesting. These riots were organised by the far right who were waiting for the exact moment a high profile incident like Stockport occurred (even if it had nothing to do with Islam), and in amongst the fascists were a pile of easily led scallies.
Racist, Islamophobic meatheads in Tommy Yaxley-Lennon and co. of the "English" Defence League don't know much about English history. Surely to be a member of such a group you have to have some knowledge of the English?
I suspect most of them cannot read, so perhaps a prison officer can read this to them in due course:
— Voltaire in Letters on the English in 1733:
"Take a view of the Royal Exchange in London, a place more venerable than many courts of justice, where the representatives of all nations meet for the benefit of mankind. There the Jew, the Mahometan [Muslim], and the Christian transact together, as though they all professed the same religion, and give the name of infidel to none but bankrupts. There the Presbyterian confides in the Anabaptist, and the Churchman depends on the Quaker’s word. At the breaking up of this pacific and free assembly, some withdraw to the synagogue, and others to take a glass. This man goes and is baptized in a great tub, in the name of the Father, Son, and Holy Ghost: that man has his son’s foreskin cut off, whilst a set of Hebrew words (quite unintelligible to him) are mumbled over his child. Others retire to their churches, and there wait for the inspiration of heaven with their hats on, and all are satisfied.
If one religion only were allowed in England, the Government would very possibly become arbitrary; if there were but two, the people would cut one another’s throats; but as there are such a multitude, they all live happy and in peace."
https://www.bartleby.com/lit-hub/hc/letters-on-the-english/letter-vion-the-presbyterians/