Hundreds of cyclists have staged a "die in" on the streets of London amid concerns about road safety.
Bicycles were wheeled down Whitehall by campaigners to the British Treasury in a bid to secure increased British Government spending to protect cyclists.
Protesters are demanding British Chancellor Philip Hammond increases ringfenced infrastructure expenditure on cycling and walking to 10% of the transport budget.
Many attending wore gas masks as a symbol of their anger at the worsening air pollution crisis gripping the capital.
The tinkling of bicycle bells provided the soundtrack to the march as chants of "stop killing cyclists" rippled up the crowd.
One sign read: "We are all canaries in London's toxic air."
Five people - three cyclists and two pedestrians - have died on London's streets in the last week.
Several people wore pictures of the victims pinned to their lapels.
In the shadow of the Treasury, campaigners lay down their bikes and dropped on to the wet tarmac for a minute's silence.
Co-founder of campaign group Stop Killing Cyclists Donnachadh McCarthy said: "They keep announcing breadcrumbs and they think we are fools.
"We have had enough of the breadcrumbs - we need real spending.
"We have had two tiny superhighways built, but they have been a huge success. They are the germs of a revolution which should spread all across London."
He told the crowd outside the Treasury building that they hoped the Government would match the proposed spending increase by 2020.
Stop Killing Cyclists spokesman Caspar Hughes said: "Air pollution is poisoning millions of people in the UK, whilst traffic carbon emissions are contributing to the climate emergency.
"Road danger means most people do not feel safe cycling on UK roads, which means they lack life-saving physical exercise."
Their warnings follow a renewed crackdown on dirty air from Mayor of London Sadiq Khan.
Last month, he issued the first "very high" pollution alert for the capital, as swathes of the UK suffered from very high or high levels of pollutants known as particulate matter choking the air in the still, cold conditions.