As Pope Benedict travels across Britain over the next four days he will followed by an army of press photographers documenting his every public move.
But only one person will be able to follow him up-close over the entire trip. Marcin Mazur was a student and hobby photographer when he walked into Westminster Cathedral four years ago and asked staff if he could take pictures of the inside of the church.
That day was the start of a remarkable journey which would eventually give him near unfettered access to the leader of the world's Catholics.
The Polish-born student, currently studying at the University of West London, has been appointed as the Pope's personal photographer for the duration of his visit to Britain. While press snappers jostle with each other in specially designated pens and shoot from afar, the 34-year-old will be able go where he pleases and photograph what he likes.
"It's an amazing privilege," he said. "[The Pope] is a very humble person. When I'm in front of him taking photographs I'm almost ashamed that I have to disturb his praying. For an 83-year-old man to be in front of 25 cameras all the time is not easy so I always feel a little bit sorry for him. But I also understand that my position is to take photographs to show to people who can't be there."
Officials at the Catholic Church in England and Wales were so pleased with Mr Mazur's shots of Westminster Cathedral that they asked him to cover future events. As he was studying photography at the time, it allowed him to build up an unparalleled portfolio of behind-the-scenes images.
He created a Flickr account for the Church which now has one million subscribers and syndicates images to the millions of faithful around the world. In the past four years he has covered papal visits to Poland, Germany, Australia and Portugal.
"Photography is a way to interpret what is happening around you," he said. "I like to be able to try and send a message to people through my photographs."
A chance discovery of a photograph of his brother originally made Mr Mazur fall in love with the camera. "When I was a young boy I found a photograph of my brother who died very young," he explained. "I did not know about him until I found the photograph when I was 10 years old. I asked my mum who that baby was and she said it was my brother. It was a very special moment for me because I was able to meet a person I'd never heard about through a photograph."
As a devout Catholic he has been dismayed by the criticism aimed at the Pope. But he believes the country will be firmly behind the visit once Benedict touches down on British soil.
"When I went to Sydney there was lots of debate in the media about how [the Pope] wasn't wanted in the country," he said. "But when he arrived in Sydney and met people, the atmosphere completely changed. I think the same thing will happen here."