Police face having to rethink their whole strategy for public demonstrations after judges ruled today that the surveillance they placed a peaceful protester under was unlawful.

The Court of Appeal ruled that John Catt’s human rights were breached when he was placed on the police’s National Extremism Database despite never having been involved in any crime.

The move means that officers will not be able to record details of people who join demonstrations, simply because they are there. And it calls into question one of the most useful tools available to officers when patrolling protests.

Download the new Independent Premium app Sharing the full story, not just the headlines

“I hope this judgment will bring an end to the abusive and intimidating monitoring of peaceful protestors by police forces nationwide. Police surveillance of this kind only serves to undermine our democracy and deter lawful protest,” said Mr Catt, 88, after the judgement was handed down in the High Court.

Mr Catt’s solicitor Mr Shamik Dutta of Bhatt Murphy said: “This judgment exposes the widespread and sinister nature of police surveillance of ordinary members of the public in this country. It also acts as a safeguard against the creeping criminalisation of peaceful protest. The Association of Police Officers and Metropolitan Police Commissioner have sanctioned this unlawful conduct for almost a decade and must be made accountable”.

Today, following a hearing at the Court of Appeal in January, Master of the Rolls Lord Dyson, Lord Justice Moore-Bick and Lord Justice McCombe, announced that they had allowed Mr Catt’s appeal against that earlier decision.

The appeal judges said the inclusion of personal information relating to Mr Catt on the database “does involve an interference with his right to respect for his private life which requires justification”.

They said they had reached the conclusion that the “interference with Mr Catt’s right to respect for his private life has not been justified and that the appeal must therefore be allowed”.

Mr Catt was not present in court for the ruling.

James Welch, legal director for Liberty, said after the ruling: “ Intelligence-gathering is a key tool of modern policing but peaceful protest is crucial to our democracy and must be protected.

“The court rightly recognised that the routine retention of personal information about a committed but always peaceful protester was a clear breach of his privacy and of no identifiable use in terms of intelligence. As such it simply cannot be justified.”

A joint statement issued by the Association of Chief Police Officers and the Metropolitan Police indicated that they were “ disappointed” with the judgement and were still considering whether or not to appeal today.

It read: “Police databases, including those containing data on domestic extremism, are maintained in compliance with the Management of Police Information (MOPI) statutory code of practice. This provides a framework for the collection of information for policing purposes. The National Domestic Extremism Unit (NDEU) database is maintained according to these principles.”