He's walking down the Champs-Elysees when his mobile phone rings. "Fr Troy, the cops are all over Ardoyne, what's going on?" the caller asks. He's strolling through the Jardin des Tuileries when somebody texts: "The Orangemen are marching here tomorrow, will there be trouble?"
Aidan Troy might have left Ardoyne but Ardoyne refuses to leave him. It's almost a year since he was moved to Paris in controversial circumstances. He wanted to stay in north Belfast, and the people wanted him. He doesn't know the answers to the phone calls and texts he receives but he's touched that the community keeps turning to him.
For three months, he walked the Holy Cross children and parents to school through a vicious and violent loyalist protest which made international headlines. That image of the priest and the people, side-by-side, led a tough working-class district, not known for sentimentality, to let Fr Troy into its heart.
But the church always feels threatened when one priest becomes too popular. Last September, Troy (63) was moved somewhere it was thought he'd fade into oblivion, where there'd be no causes or crusades. St Joseph's is a quiet, mainly wealthy, English-speaking parish in Paris.
Yet his old parishioners keep finding him. Troy was born in Bray, Co Wicklow, but it is Northerners who have the deepest affinity with him.
"Not a week goes by that somebody from Ardoyne doesn't visit Paris," he says. "I'm regularly at Eurodisney with families. There I am on rides – white-knuckled from gripping the rails, and speechless with fear – while the children throw their hands in the air and squeal with delight."
Troy's telephone and door-bell ring at all hours. "People call and say: 'Father, we're coming to Paris, which hotel should we stay in?' They turn up on the doorstep asking what sights to see. I take them to the Louvre, Notre Dame or wherever they want.
"Sometimes, they're not even from Ardoyne. They're from west Belfast or Derry and I've never met them before. They just know about Fr Troy and the Holy Cross protest and think, 'He'll sort us out'."
He takes them on walking tours. Up to Sacre Coeur, around Montmartre and back through Pigalle – home of the Moulin Rouge and Paris's sex district.
"It gives them a genuine feel of the city," he says.
St Joseph's, a two-minute walk from the Arc de Triomphe, has a 2,000-strong congregation which spans 40 nationalities. Troy embraces the racial mix. He's been at the Fillipino National Day breakfast, Sri Lankan independence celebrations, and even a British embassy event for Commonwealth Day which the Queen addressed by video link – "I hope the lads in Ardoyne didn't hear about that!"
St Joseph's is a modern church in the underground part of an office block. It's not a 'normal' local parish. Parishioners live up to 30km away. The common bond is that they want to attend an English-speaking mass. Troy and an American priest, Francis Finnigan, live in an apartment above the church.
RTÉ's Pat Kenny brought his family to mass the other week. He was married in St Joseph's and wanted to show his daughters the church.
So how is Troy settling in? Ardoyne's issues of riots, paramilitaries, drug abuse and suicides – Troy buried 30 young men who had killed themselves – aren't those of St Joseph's.
He has experienced other non-Irish parishes: he spent seven years in Rome and two in San Francisco, "an extremely hard city to leave". But his new beat is very different to his last one.
"On my morning walk to Ardoyne shops for the paper, somebody would ask me to sign a mass card. Somebody else would say, 'Father, will you visit my sick mother in hospital?' Another person would ask, 'Father, my daughter's pregnant, how can she get a house?'
"I miss all that, but there are other challenges here. It's a more diverse parish than people think. We have senior embassy staff and illegal immigrants. The Fillipino ambassador might be sitting in church beside a Nigerian with no papers.
"I feel for the illegal immigrants. They've a tough existence, living with constant insecurity and often exploited by employers. I give them what support I can." Sometimes, a priestly word in the ear of a powerful parishioner can sort out an illegal immigrant's problem.
Troy jokes that some American parishioners aren't always what they seem: "One man leaving after years in Paris gave me his card and told me to call if ever I was in the US. He was in the secret service, but he wouldn't tell me until he was going."
After Sunday mass, Troy's passion for his new parishioners is clear. He stands outside the church to personally greet everybody leaving. "Hello sweetheart!" he says, embracing one little girl and her parents.
An American couple, Maureen and Andy Yu, have just arrived with their three children to live in Paris. "Father, we're delighted to find yourself and St Joseph's," Maureen says. "And my granny was a Brennan from Co Cork!" Then, Troy is off to baptise twins from Togo whose parents arrive in full national costume.
South African Michael Haas, who teaches catechism at St Joseph's, says: "It's a difficult place for any priest to fit in, particularly an Irish one coming from a close community. Apart from weekend masses, the priest is isolated all week. Fr Troy's ability to adapt is awesome, and he's using his remarkable social skills to pull the congregation together and create a sense of community."
Haas's three-year-old son David sits in the pew waving to Troy during the Eucharist. The warmth the priest brought to Ardoyne is replicated in Paris: "I'm not half-hearted about this parish or its parishioners – they're super people. They deserve, and have got, a priest totally committed to them, not one battling to be transferred back to Belfast.
"I could have sat licking my wounds saying 'Oh poor me, look how the church treated me!' But as somebody said, 'You were sent to Paris, given a job, an apartment and a car. You'll never go hungry and you'll always have a few shillings in your pocket'."
Paris certainly has its plus sides. Troy loves "the brightness, the sunshine and the buzz of driving around the Arc de Triomphe wondering, 'Will I hit somebody, will they hit me?' He has picked up the language so well he passes for a Parisian. In a restaurant, we're handed the French, not the tourist, menu.
He's healthier too. The nights of "too many pints in Ardoyne GAA club" have been replaced by the odd glass of wine over dinner. "Salads and snails are very different to my Belfast diet," he says.
"I no longer need tablets for my blood pressure and I jog regularly in Parc Monceau, beside St Joseph's. I could never jog in Ardoyne. Had I been running the streets in shorts and a tee-shirt, there'd have been relentless slagging. I'd never have lived it down."
As we board the Metro to the sound of a sax, Troy jokes "It's a different experience to the black taxis in Ardoyne!"
Paris also offers glamour: "A woman phoned asking me to bless her apartment. It was Danielle Steel. A uniformed maid opened the door to this magnificent apartment with beautiful tapestries and carved animals. Danielle talked about her novels and asked if I'd ever written myself.
"I told her all about Ardoyne and how I'd written a book about Holy Cross and was writing another on suicide. She told me her 19-year-old son had killed himself. She was a fabulous woman. Two days later, a book arrived by courier to St Joseph's. Danielle had sent me her novel Amazing Grace which is set in San Francisco. I read it from cover to cover. Parts were a little racy but it was a lovely book."
Paris's liberalism doesn't faze him. "When I brought my robes to the dry cleaner's, I think he reckoned I was a cross-dresser. I just explained I was the priest from up the road."
Troy is due to remain in Paris until 2012. He doesn't know what will happen after that. When the church decided to move him from Ardoyne, the 'Keep Fr Troy Committee' gathered a 5,000-strong petition. Women threatened to chain themselves to Holy Cross's railings, but the church didn't listen.
"I agreed to go," Troy says. "I'd taken a vow of obedience years ago. Besides, refusing to leave would have been pointless. I'd have been transferred anyway and to somewhere a lot worse than Paris."
Initially, he hadn't even wanted to go to Ardoyne. "I was in Rome in 2001 when I saw the TV headlines about the Holy Cross protest. I realised in horror, 'That's where I'm going'.
"I remember walking into my first Ardoyne community meeting. One woman pointed at me and said to her friend, 'Who the f**k is that?' And her friend replied, 'I think it's the new priest.'
"I wasn't offended, I admired the bluntness. Here I was this geek from Rome and all I knew about the North could have been put on a postage stamp."
The Holy Cross protest – where the people and their priest walked to school through a barrage of bricks, bottles of urine and once a blast bomb – changed everything.
"After walking that road for three months, I'd have died for the people of Ardoyne and they'd have died for me," Troy says.
"I came to that community a deeply conservative person. Now, I haven't a conservative bone in my body.
"In Ardoyne, I realised the true meaning of faith. It's not counting the numbers in the pews. What matters is the church of the street. Without that, the church on Sunday is very hollow."
About 80% of Ardoyne didn't attend mass. "I never told them to go. I never asked whether young couples living together were married or suggested they get married. I'm sure the bishop wasn't pleased, he'd have wanted me to promote the official church more," Troy says.
"I believe in a wider pastoral role. I believe in taking up justice issues, not lecturing people.
"I wasn't everybody's cup of tea in Ardoyne. A small group of traditional parishioners would complain, 'That Fr Troy is a disgrace. There's not a riot he's not at, a TV programme he's not on, a newspaper he's not in'."
But the vast majority of Ardoyne misses him as much as he misses them. The internet means he follows everything happening at home. And it's northern, not southern, news which he reads most avidly.
He's certainly not unhappy in Paris with its sunny boulevards and majestic architecture. Yet it's Ardoyne – with its dark narrow streets, riots, poverty and proud community – where Troy's heart will always lie.