How rival protesters were kept apart by £4.5m police operation

Tourists trying to navigate major central London landmarks on Saturday were left bemused by an enormous £4.5m police operation to keep rival protestors apart.

More than 4,000 police officers were deployed to the capital to manage a so-called "sterile zone" between a rally organised by far-right figure Tommy Robinson, and a pro-Palestinian demonstration.

Nelson's Column was surrounded by metal barriers. Police officers from Wales in riot uniforms prevented anyone getting from the National Gallery to Pall Mall and Regent Street. Police vehicles lined The Mall from Trafalgar Square to Buckingham Palace.

On the steps above Churchill War Rooms, a two-meter-high metal barrier blocked the road past the Foreign Office towards Whitehall.

But there were no serious clashes between protesters on the different marches.

Every year, pro-Palestinian protesters hold a march on the weekend closest to 15 May to mark the Nakba, the displacement of Palestinians who fled or were driven from their homes during the war surrounding Israel's creation in 1948-49.

But when organisers started talking to the Metropolitan Police about this year's march, they discovered 16 May had already been booked by anti-Islam campaigner Robinson, whose real name is Stephen Yaxley-Lennon, for one of his Unite The Kingdom marches.

After negotiations, it was agreed that both marches could go ahead, but it meant a huge security headache for the police force. Not only were there two rival marches, but the FA Cup Final at Wembley also fell on Saturday.

It meant the Met had to stage one of its most significant public order policing operations since the May Day riots of the early 2000s.

The operation's aim was to maintain the principle of freedom of speech - that people should be allowed to express their political views, so long as hate speech laws were not broken.

But officers'concerns were high because the last time Robinson staged a march, an estimated 150,000 turned up. A few of his supporters had running battles with the police as they tried to get close to anti-racism campaigners at the other end of Whitehall.

Of the thousands of officers drafted in on Saturday, 660 of them were from other forces in England and Wales under what is known as mutual aid.

Senior officers devised a sterile buffer zone between Trafalgar Square, Buckingham Palace and Parliament Square.

The Unite the Kingdom protesters were able to walk from Holborn, along the Strand, down Whitehall and into Parliament Square for their rally.

Those on the pro-Palestinian march were allowed to make their way from Knightsbridge, along Piccadilly and into Pall Mall for their speeches.

The plan to keep the two sides apart seems to have largely worked.