By Megan Lane
BBC News, Heathrow
As planes roared towards take-off on the other side of the busy dual carriageway, a trumpet and whistle played nursery rhyme Incy Wincy Spider for protesters arriving at BAA headquarters at Heathrow Airport.
Many protesters dressed up as clowns for the occasion
The protesters, most in wet weather gear and many wearing clown wigs, began setting up mobile pop-up tents in the BAA car park under the watchful eye of police in riot helmets bearing plastic shields.
To minimise disruption to the handful of BAA staff at work on a Sunday, the police tried to contain the protesters in the corner of the car park.
When activists made up their own minds about where to take up positions, police shields were used to push them back.
Each handful of protesters arriving on the scene was greeted with claps and cheers.
Where many had been part of the climate camp at Heathrow throughout the week, others arriving at BAA came just for the day.
Pete Caunter, 54, from Bexhill-on-Sea, East Sussex, was among those taking part in the day of action.
"I was hoping there would be a proper march," he said as a group of about 30 protesters tossed around an inflatable globe.
"I'm concerned about pollution of all kinds but increasing flights are at the top of my list.
"I last flew in 1990 to Jersey for a wedding because there was no other way of getting there. But apart from that I have not flown since the 1970s."
'Making a change'
Anne Notley, of West Sussex, also came along for the day.
"I feel that middle-class professional people have to make a stand because we are among the worst culprits. I have been a culprit too," she said.
After many years of flying while running her own business and taking overseas holidays, she has now decided to travel only by land and sea.
There were a number of minor scuffles throughout the day
"We were going to fly to Greece to adopt two dogs but now we have decided to take a driving trip instead.
"It's not much but I'm making a change."
Jane Gregory, a rape crisis worker in her 40s, had been at the camp all week.
"This is my summer holiday," she said as she sat in the BAA car park.
She said she had decided last summer that she would never fly again.
"Soon after, that I went on holiday with my mother and sister to Rome and I went by train."
Hours after the first climate change protesters arrived outside BAA to stage their sit-in, the carnival cavalry arrived.
Dance music and A Spoonful Of Sugar, from the musical Mary Poppins, were played on a bicycle sound system.
In the newly-arrived crowd were bongo drummers, magicians, jugglers and small children fast asleep in all-terrain buggies.
The 100-strong group was made up of families and members of the local community who had made halting progress from the camp.
Santokh Singh Dhillon, a Hillingdon councillor, lives just half a mile from the protest site and represents many of those who took part in the march.
Santokh Singh Dhillon is a local resident and council member
Mr Dhillon said he was there as an observer as well as a supporter of the protesters.
"Many people in my ward are fed up," he said.
"Their houses are at risk of being demolished to make way for the runway if it goes ahead, but they [BAA] will decide the market rate.
"How fair is a market rate? Who would buy my house if they knew it was going to be demolished?"