Behind the pebble-dashed walls of the little cottage in north London lies a modern-day Santa's grotto: 35 tonnes of toys and food, stacked to the rafters.
Teetering towers of goods cover the floor in every room: toys in the dilapidated garden shed out the back; gadgets and gizmos in the living room, including two electric scooters and a remote-controlled Focke-Wulf aeroplane, propped up by layers of Christmas hampers. The coffee table, meanwhile, is strewn with high-visibility jackets, comedy hard hats and home-made badges bearing a peculiar drawing of "Uncle Sam" dressed as a clown.
The resident, David Goodfellow, 29, and his housemates are spontaneous do-gooders who go by the name "The Kindness Offensive". They specialise in meting out random acts of charity to unsuspecting members of the public.
The reason their Hampstead home resembles a warehouse is because they are in the middle of receiving £250,000 of toys and food which they managed to persuade charitable companies to give to them for free. On Monday they will distribute 3,500 hampers and giveaway thousands of presents across north London housing estates from the top deck of a specially painted double-decker bus.
It is the biggest single act of kindness yet from Mr Goodfellow, Benny Crane, 26, James Hunter, 22, and Callum Teach, 29 – and, they say, a reminder that ordinary people are capable of extending a charitable hand should they wish to do so.
"Not that I want to come off sounding preachy," says Mr Goodfellow, "but I firmly believe that deep down most people are good. They genuinely want to help others and when they read about something tragic they feel bad. They sit at home on their sofas wondering how they might be able to help people but they never get round to actually doing it. Our movement is about showing people that there is nothing to stop you doing good deeds."
The process of getting hold of random items to give away is, they say, remarkably simple. You simply phone endless manufacturers to see if they are willing to donate something – a process they call "phone whispering".
"You have to make a lot of calls," Mr Goodfellow explains. "Our phone bills look more like a phone book but eventually you reach someone sympathetic."
Iwantoneofthose.com has provided many of the gifts while Vinspired.com, a website that specialises in getting teenagers to volunteer, is providing a 60-strong army to help give them away.
Inspired by the growing number of groups around the world that specialise in spontaneous generosity – the "World Kindness Movement", for instance, has 20 affiliate groups in 17 different countries – The Kindness Offensive is all about those random acts of generosity that can make a person's day.
"I feel like we live in this climate where everyone is taught to mistrust each other," says Mr Goodfellow who recently gave up being a chef in order to organise events for NGOs and charities. "We're told to report suspicious behaviour and keep an eye on what your neighbour is up to. We're never encouraged to help each other out."
The quartet began touting their services a year ago on Hampstead Heath where, dressed in high-visibility jackets complete with comedy hard hats, they set up a stall and proceeded to ask random members of the public how their lives could be improved.
"It took a long time for anyone to believe that we were genuine," said Mr Crane, a musician. "Most people were deeply suspicious, they thought we were Mormons or Jehovah's Witnesses. Those that did entertain the idea, I think, generally saw it as a bit of a joke. They never expected we'd live up to our promises."
Their first successful "kindness act" was to persuade Yamaha to donate a red guitar to a boy who they knew wanted one. They have since followed that up by sending someone to see the Moscow State Circus, fulfilling another person's dream of seeing a match at Wembley and, in October, they distributed more than 25 tonnes of food to destitute asylum-seekers. "They way we treat asylum-seekers is appalling," said Mr Harding, who until now has let the other two housemates do most of the talking. "We've met people who are literally living on pennies each week. They have often escaped the worst sort of persecution, desperately want to contribute to society and yet cannot even afford food."
Mr Goodfellow adds: "Meeting asylum-seekers has opened up our eyes to a shocking world. These people are forced to live on handouts because they are not allowed to work. The handouts they do get often lack some of the most basic items that we take for granted like nappies, toothpaste or condoms. And all this is happening right under our noses or outside our front door."
Until now the men have been extremely publicity shy – The Independent only found out about the food deliveries when an impressed neighbour phoned up and encouraged us to visit. All four members of The Kindness Offensive say they would like to see more people performing kind deeds for one another.
Michael Goodfellow, David's father, is the latest convert to sign up. "I knew they were up to something big but I had no idea it was this big," he said, gaping at the interior of the cottage. "What I've learnt is that kindness is infectious. Just look at what happened with the neighbours. If you do good deeds others will follow."
Secret (and not so secret) Santas
Otherwise known as the "Kansas City secret Santa", Stewart, who made his fortune through cable television sales, made a habit of anonymously handing people a single $100 note in the street. He started the tradition in 1979 after twice losing his job just before Christmas. By the time of his death last year he had handed out $1.3m and revealed his identity to encourage other secret Santas.
In the 1960s, the US computer millionaire and former presidential candidate decided to give a Christmas present to every US PoW in Vietnam. After he hired a fleet of Boeing 707s to deliver the gifts to Hanoi, the Hanoi government said the gesture was inappropriate when villages were being bombed by B-52s. So he sent his planes to Moscow, where his assistants posted the parcels one-by-one from the central post office. They arrived in the PoW camps intact.
*Sir John Paul Getty Jnr
The US-born heir to his father's oil fortune made his home in Britain. He had a reputation as a hedonist before settling down to redistribute his share of the family wealth. During the 1984 miners' strike, he donated £100,000 to the Christmas appeal fund, declaring he was the "custodian of money for the benefit of people who need it more than I do". He later made contributions to the Tories.
*James Gordon Bennett
A 19th-century Scottish-born publisher and journalist who founded the New York Herald. One Christmas he gave a tip of $14,000 (about £150,000 today), to the guard on the Train Bleu between Paris and Monte Carlo. The beneficiary left the train at the next station, resigned, and opened a restaurant.