Sadiq Khan calls for resilience ahead of London's New Year fireworks show
London is "as safe as it possibly can be", city mayor Sadiq Khan said as he rallied crowds to stay resilient ahead of the riverside fireworks display to ring in 2017.
A huge police presence was on the streets as spectators from almost 100 countries began to flock to the Capital's River Thames to view the spectacular pyrotechnics, which will begin painting the night sky as Big Ben strikes midnight.
Around 12,000 fireworks producing 50,000 projectiles will transform the city skyline for 12 minutes, enchanting around 110,000 ticket holders at the sold-out mayor's showcase event.
Mr Khan said the mood on the streets was "upbeat", adding it was "really important we don't allow terrorists to disrupt our celebrations on this New Year's Eve".
He told the Press Association: "It's as safe as it possibly can be.
"We've done everything we possibly can do to keep us safe. We've got more armed police officers on duty tonight than we have on any previous year, we've got more visible police officers working tonight than on any previous year, covert teams have been working their socks off, security services, the Metropolitan Police Service, the British Transport Police and other partners have been working their socks off.
"We do all that we can to keep us safe. Just like the bad guys evolve and find new ways to harm us, we've got to find new ways to evolve and to keep us safe.
"We've got to make sure the resilience that London is famous for is demonstrated tonight."
Thousands of police officers will provide a protective ring around the city's fireworks display, while tactics have been adjusted following this year's terrorist atrocities in Europe.
Around 3,000 officers will be on duty within and outside ticketed areas, while armed police will be a fixture on the capital's Tube trains as they travel between jobs in a move aimed at reassuring passengers.
Fears of a mass-casualty terror plot targeting one of the country's New Year events have heightened after lorries were used in devastating attacks on crowded areas in Nice and Berlin.
British Transport Police (BTP) said they would also be extending officers' working hours on the night for a second year running.
BTP Superintendent Andy Morgan said: "We developed and improved our security plan for last year's New Year's Eve event following the atrocities in Paris in the previous November and we, of course, have looked at good security, a thorough security boost following a different type of threat in Nice back in July."
For the first time, people without tickets will be able to view the fireworks from three locations through a 360 degree live feed on the BBC that will start at 11.50pm GMT.
This year's feverish countdown will also last longer than usual - an extra second - as a so-called "leap second" is introduced to compensate for a slowdown in the Earth's rotation.
Some of the stars the world lost in 2016 will be honoured as singer David Bowie, American superstar Prince and the Two Ronnies, which included the late Ronnie Corbett, are to feature in the soundtrack.
Mr Khan said he had been concerned "bearing in mind what happened in Berlin about safety in London", but that it had been a great Christmas.
Wishing everybody a happy new year he added: "People are optimistic about the future, even people who maybe were down in the dumps about the vote to leave the EU, as Remainers understand that actually now we've got to make a success of it.
"So you know I want to bottle up that energy and enthusiasm into 2017."
In Edinburgh, the world-renowned Hogmanay street party will see 80,000 punters flock to the city centre to enjoy music from The Charlatans, while Paolo Nutini fronts a concert in the gardens.
The weather was mild and dry in the capital, and the red dome of the London Eye stood clear against the night sky with most of the morning's heavy fog having lifted.
With more than four hours to go, the first rows of spectators in London had formed as crowds eagerly awaited the new year along 16,800 metres of barriers.
But the New Year enthusiasm is at risk of being dampened in northern England and Wales, as rain is set to sweep across areas including Manchester, Leeds and possibly Cardiff at midnight, the Met Office said.
Xintong Chen, a Master's student in urban design at the University of Manchester, was at the front of the crowds directly opposite the London Eye.
Her mother, who she has not seen in almost a year, turned 50 today in China.
She said: "Today is very important for me because it's my mother's birthday.
"I miss her very much. I think it's very meaningful to have new year in this place.
"Today I want to show my love to my mother," she added, holding up a home-made birthday card.
The 25-year-old from China said she had been nervous about coming to London following recent terrorist attacks in Europe, but that she felt "very safe" tonight.
She said: "My mother is really worried about it, but I think London is a very safe city.
"This country gives us many things to learn compared with other countries, you can relax yourself, enjoy your time, enjoy life in this place, I think it is the best country in the world."
Adnaan Ahmed, 23, said he had been waiting to get into the ticketed Embankment area since 4pm, and managed to get a spot right at the front of the crowds.
The 23-year-old from Bolton, near Manchester, said: "I've been waiting five years for this moment.
"It's been a moment I've wanted to do for a long time, but I've finally got the chance to do it - with family.
"Everyone's been very friendly. It's a fun environment to be in, the people are nice, it's been a great welcome," he added.
Asked if had had any concerns coming to London on New Year's Eve he said: "No, none whatsoever. It's a beautiful city, everyone comes, we all come together."