A Hemel Hempstead man was among a group of protesters jailed for attacking police officers at pro-Tommy Robinson demonstrations.
Danny Grealey, 43, of Ebberns Road, threw a traffic cone at police when he was on the protest in central London in June last year.
Others hurled glass bottles, scaffolding and various makeshift missiles during an afternoon of "serious disorder" in the capital.
The demonstrations caused major disruption to members of the public, businesses, and the local community.
Grealey, appearing at Southwark Crown Court on Friday, September 27, was sentenced to 18 months in prison for violent disorder.
In total, 14 protesters were jailed for a combined 18 years.
Robert Hutchinson, prosecutor from the London CPS complex casework unit, said: “The terrifying disorder wreaked by these individuals in the heart of London was inexcusable.
"Protesters set out to intimidate and hurt police, injuring more than 20 officers who were protecting the public and tourists in Central London on the day of Trooping of the Colour, and who should have been able to go about their duties without fear of violence.
“This was a complex case and has involved exceptionally close liaison with the police from an early stage to determine appropriate charges that reflected the seriousness of their crimes. The strong case we built ultimately left the defendants with no choice but to plead guilty.
“The sentences passed should serve as a warning that those who direct violence towards police and act in this way will face prosecution and potentially prison.”