Máirtín Ó Muilleoir, Lord Mayor of Belfast for one more week, likes to take selfies and post them on his prolific Twitter feed. There are pictures of him with pink hair for the Giro d’Italia, at fun runs, with school children, with choirs, with campaign groups, local communities, fellow politicians and local businesses. The tweets fly thick and fast. At one point he snaps my photo so he can tweet it. In person he’s even faster than his Twitter account. He jokes, quotes, informs, electioneers and is prone to sudden changes of direction, gently taking hold of my elbow to manoeuvre me with him as he goes. He wants to represent “a new Belfast”.

“This is what we call a ‘shared space’,” he says, as he guides me around the Lord Mayor’s Parlour in Belfast City Hall. “Can you remember those two words, Patrick?” he says.

“Shared space,” I say.

He talks quickly, is very funny and asks me questions like a teacher.

“What’s the most successful sport in Belfast?” (It’s ice hockey, apparently.)

“The biggest parade in Belfast is?” (The Pride parade.)

“What’s that flag?” (The flag of the Philippines.)

“Why have I a picture of Rosa Parks?” (Because her maiden name was the Scots-Irish McCauley.)

“What are the two most important words in Belfast?”

“Shared space?” I say, tentatively.

“No,” he says. “Diversity and inclusion.”

There’s a lot to take in. There are two paintings by William Conor, one of an Orange parade, one of hurlers at Falls Park. There’s a 12th-century Irish poem on the wall, a scarab that was a gift from the Egyptian community, a scroll from the Chinese community, an ornamental elephant from the Indian community, and a teddy bear from the organisers of Pride.

“Everyone is a minority in Belfast,” he says. “Protestants are a minority. Catholics are a minority. The Chinese are a minority, the Poles, the Africans. I think we all need to accept that. The minorities will save us from ourselves.”

Among these symbols of a new Belfast are relics from an older one. I ask about the silverware. We peer in at one piece. It references the Royal Ulster Rifles. He grins. “Maybe find something less contentious.” The next one involves the Royal Sussex Regiment. “I’m going to get in trouble here.”

God save the queen’s portrait

The room also features portraits of Queen Elizabeth, the Duke of Edinburgh and the Queen Mother, sitting across the wall from the Declaration of Independence. "And they haven't had an argument all year," says Ó Muilleoir. "When I was elected we said, 'We're not going to remove the royal portraits', and you could just feel the tension easing." The previous Sinn Féin mayor removed them. He's also content to be called "lord mayor" if that's what people want to call him. Unionists like the term; Sinn Féin mayors in the past have not.

It’s “a sweet irony” for Ó Muilleoir that as a Sinn Féin councillor in the 1980s he was barred from the Lord Mayor’s Parlour. He joined the party in 1981, and went into Belfast City Council in 1987. “I used to wear a flak jacket to work. They were shooting Sinn Féin councillors. We weren’t allowed to speak. We went to court. We won a succession of cases. I could bore you to tears with all this.”

He’s written a book about that era, but he doesn’t really want to talk about the past. His family were involved in the peace movement in the 1970s after his mother’s friend Martha Crawford was shot dead in a gun battle. Their windows were broken because of their involvement in that movement. “It may have been the IRA,” he says. “I can’t remember now. But this is a time of great polarisation, a time of terrible grief and loss, and in any war civilians suffer most. There were gun battles on the street. It was surreal. You can’t understand what that means getting up every day and going to school. Anybody from my area can tell you where to position yourself when there’s a gun battle.”

He left politics in 1997 because "I was getting fed up of people trying to kill me". He also had an opportunity to take over the Andersonstown News. His Belfast Media Group now owns a number of newspapers including the New York-based Irish Echo. In 2004 he started Daily Ireland, an attempt at an all-island republican newspaper. That was pretty ambitious, I observe. "Why didn't you tell me that at the time," he says. It closed a year later.

In 2011, he returned to local politics and a very different City Hall, because he was worried about inequality. “You can’t expect people to back the peace if they don’t see and taste and feel the evidence. We’re in danger of having a tale of two cities.”

Belfast can’t go backwards, he says. He recounts the life stories of some City Hall employees I have met who have suffered in the conflict. “In this place, everybody’s hurt,” he whispers. “We come from a place of horror. We don’t want to go back there. We in Belfast have suffered terribly, and my prime goal in life is that we build this peace and don’t go back to that.”

He shows me the council chamber where unionists once dominated and where he sits "on a chair that's so heavy it's on tracks". We pass the portraits of previous mayors. "There's Sammy Wilson, a very good finance minister," he says. "I fought him in the chamber once." He turns and looks at me. "And when I say fought, I don't mean metaphorically."

What did they fight over? “Ach, it’s in the past. It should be left back there.”

He gets on well with his counterparts. He recently brought the DUP’s Sammy Douglas to a Mass. It went on a bit long. “Sammy said, ‘I have a DUP constituency meeting in five minutes. What am I going to say when they ask ‘where were you?’ ‘I was at Mass’.”

In the entrance hall, an American tourist in a San Francisco T-shirt is taking a photo. “I was just saying to Patrick that San Francisco is my favourite city,” says Ó Muilleoir. They get a picture together.

The mayor’s driver, Philip Purdy, has seen many mayors come and go and worries future mayors won’t keep up his good work. “When it’s over, it’s over. Twelve o’clock on June 3rd,” he says.

“There should be some transitional period where you’re allowed some delusion of power,” says Ó Muilleoir.

We drive to the Lisburn Road where, after lunch, he canvasses for the council elections. (Two days after we meet, he tops the poll in Balmoral.) On the street we chat to two local businessmen. One applauds him for meeting the queen at Windsor Castle in April. “I didn’t know it was the queen!” Ó Muilleoir exclaims. “I thought we were going to see a Queen tribute band.”

To me, he says: “It was something we had to get sorted. You can’t be the first citizen of a great city like Belfast and have a list of people you don’t meet.” He is also the first Sinn Féin mayor to attend an Armistice Day event.

We canvass on. He is gently chided by the mother of a local businesswoman: “What are you doing for young people starting businesses?”

Sinn Féin isn't always seen as the party of business and he insists that his businesses are small ("They're not IBM," he says at one point "though I like IBM"), but he has led several trade delegations and seems to enjoy chatting to entrepreneurs.

More people come over to talk. On April Fool’s Day, Ó Muilleoir put on a Batman suit and had a motion before council to have a “superheroes day”, so a little boy tells him that his favourite superhero is Spider-man. “I don’t like bad guys,” the boy says.

“I don’t like bad guys either,” says Ó Muilleoir.

We meet the retired SDLP MP Joe Hendron and his wife, Sally. “A big contributor to the peace,” says Ó Muilleoir.

“I’ve been following you on Twitter,” says Sally, “to see all you get up to.”

A year as mayor

He has enjoyed his year as mayor. He shows me emails from unionists praising his mayoralty. He’s particularly proud of a letter from a woman from a loyalist area whose mother he had met in a hospice. She wrote that he was “a mayor for all”.

It hasn’t always gone smoothly. Last August, when opening a park, he was attacked by loyalist protesters. “It was just a bad moment,” he says. “I took a very bad kick, a police officer was injured. Some people put out a statement saying my visit would be an affront to that community, and in my view that created the circumstances in which some people who aren’t particularly clever, and can be wound up, engaged in the attack. But no one has dared say, since that day, that the lord mayor’s visit would be an affront.”

He is a positive man. “My Buddhist chaplain [he has appointed eight different chaplains] says ‘edit out the negativity’,” he says. “We need to acknowledge that where we’ve been is a terrible place, that we’re never going to agree on the past but we’re going to try and build something for the future.”

On the way back in the car he chats about his four children, all in college (one is canvassing for a rival candidate) and watches what’s going on outside the window in his city. He spots a photo shoot. “Why wasn’t I told?” He sees a gathering of PSNI vehicles and goes on Twitter to see what’s going on. “That’s possibly the longest time I’ve been off Twitter,” he says. “Once I was away for three hours and somebody asked if I was okay.”

He doesn’t want to be known as “the former lord mayor,” he says, but when I ask, more than once, about his political ambitions, he is coy. He references his Buddhist friend’s advice that he should live in the now. “I don’t have a master plan,” he says, then pauses and looks at me. “Why, what job are you giving me?”