(Top photo: Loughery outside Westminster Abbey. Photo: Yui Mok/PA)
I first encountered him at the vigil for the Westminster attack victims in Trafalgar Square. It was a sombre affair packed with dignitaries, the press and hundreds of determined Londoners, battling to light candles against the brutal wind.
Over the gentle hum of consolations I heard a squeaky-voiced gentleman, draped in a Union Jack flag, begging photographers to take his name and offering solo shots, apparently bathing in the glow of this horrific event.
One disgruntled photographer mumbled, "Fucking Diana Man is in every shot!" and jabbed a finger in his direction, as his image was beamed around the world.
I later learned that "Diana Man" is actually a guy called John Loughery, a self-described royalist who has been photographed and interviewed dozens of times outside royal events. He earned his moniker after attending every day of the six month inquest into Diana's death. Most recently he waited through rain and freezing nights for two weeks outside the hospital he knew Kate Middleton was going to give birth in.
I wanted to understand what it was about public memorials that made him paint his face like he was heading to watch Andy Murray after downing ten beers. So I tracked down his inactive Twitter account, with the bio "world renouned Diana fan [sic]", with little luck. I tried him on Facebook, too – where his profile picture is of Princess Diana, obviously – but got no response there either.
I eventually stumbled across a local newspaper article in which he described his anxious wait for the birth of Prince George. Crucially, it yielded a road name, and with nothing else going on in my life I set off on my quest to find Diana Man, leaving notes with neighbours in the hope he would contact me. Eventually, he did, and we set up a meeting in Trafalgar Square.
Back in 1997, John gave up his job as a hotel chef and moved in with his sister so he could camp for four days outside the Royal Courts of Justice to be the first member of the public at Princess Diana's inquest. As a sign of his devotion to finding out the truth, he painted "Diana" on his forehead and "Dodi" across his cheeks.
"I didn't know what else to do to show my respect," he explains. "There were so many conspiracy theories knocking around about the Queen's involvement and how she was murdered; I had to be there to see the truth with my own eyes. I was hoping in my heart that it was all lies, and it was."
John was the first to get a ticket to the inquest, which would reveal the exact circumstances surrounding Diana's death and cut through the media-powered national hysteria.
Shocked by how few members of the public attended, John managed to get his ticket signed by all the people who gave evidence, including Diana's grieving sister Sarah McCorquodale, and is now planning to auction it off in aid of Prince Harry's charity, Sentebale. He even managed to somehow charm his way into taking home the two miniature cars used by the inquest so he could reconstruct the fatal crash that stole "England's Rose" away in 1997, and was praised by Lord Justice Baker in the transcript for listening to every minute of evidence at the six-month inquest.
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Now, 20 years on from her untimely death, John still can't get the image of Diana out of his head.
"I pray for her 20 times a day, in my head as I walk down the street," he says. "I tell her, 'We miss you, and thank you so much for everything you did while you were here.' It comes in my mind, her lovely smile and her eyes looking up to the sky. But I'm sure she knows about me in heaven."
To express his grief at Diana's passing more publicly, John performed a speech on the fourth plinth in Trafalgar Square. "I repeated, 'We remember Diana, I remember Diana' for an hour.' It really got the crowd going," he says. "It was very emotional, but I'm scared of heights; I was so terrified that I forgot to mention Charles."
Despite his enduring love, John was never properly introduced to the princess, and has been left with the one cherished memory of the only time he saw her in the flesh. "She was going into the Royal enclosure at Wimbledon. I regret not saying anything to her," he tells me. "She was wearing this marvellous red dress; I couldn't believe it when I saw her. I had one chance but I didn't want to intrude on her, because she was going through the horrible break-up of her marriage. I didn't want to shout out to her – that's not nice."
Along with his clique of other royal super fans, John attends Westminster Abbey every Sunday. The group's aim is to attend every national event, royal birth and, ultimately, funeral.
John tells me that if he's not at a national grieving event – whether it be 7/7, Margaret Thatcher's funeral or the vigil after the recent Westminster terror attacks – he feels guilty. "I just can't stand the thought of that brave police officer being alone," he explains.
John's passionate nationalism stems from his Irish parents, who emigrated to London in 1949. "My dad was a very private and reserved man, but on two occasions he looked me in the eye and told me, 'England looked after me.' Those words will never leave my mind," he says. "But he did think it was strange that I would stand up every time I heard the national anthem on TV."
One of John's biggest regrets was missing Diana's funeral, as his partner, Marion, was waiting for him at home with terminal skin cancer. "Marion's birthday was just before Diana died, and we had this bottle of champagne open," he says. "Then we heard the news together that there had been an accident in Paris and Dodi had been killed outright. We never touched the bottle after that.
"Marion wouldn't have minded if I went, but I thought I should probably be at home with her to watch it on TV so she wasn't alone. I didn't want to go back – trust me; I wanted to stay. That night I said to Diana, 'I'm sorry I let you down, I will never do that again, I will be there from now on, I won't feel the cold.'
"When I went back to camp outside Kensington Palace my partner would say, 'I'm going to miss you now, John.' I used to tell her leave the light on and 'I'll call you from a phonebox and you wont miss me.'"
Marion passed away on the 20th of March, 2003.
"I have two anniversaries now, for my partner, and Diana at Kensington Palace. I will always lay flowers for them both," he tells me. "When I die I will ask the Lord if I can shine down on Westminster Abbey every Sunday. I will get to see Marion and of course Princess Diana up there – and I would apologise again for missing her funeral."
During our hour-long chat John speaks at a million miles a minute, but it's only at the mention of Marion he chokes. No doubt these two griefs – one shared with millions, one entirely private – are linked for him. Yet, for someone who spends every day thinking about death, John is relentlessly positive. His way of processing grief may be unusual, but after decades as "Diana Man", it seems to be working for him.
UPDATE 13/04/17: A previous version of this article stated that Mr Loughery camped overnight on the procession route from Southwark Cathedral to where PC Keith Palmer was buried. This was factually incorrect and has been deleted.