It's one way to avoid the commute. Rosita Boland talks to three people about the perks and downsides of a home that comes with the job.

The modern equivalent of living on the job is walking the few steps from your bedroom or kitchen to a room in your house set up as a home office.

But there are some people whose job is where they live; whose homes are an integral part of the role they carry out.

There are the flagship jobs with houses to match, such as the President of Ireland's house in Phoenix Park, Áras an Uachtaráin, the US ambassador's residence opposite the Áras, and the Provost's House at Trinity College, 1 Grafton Street.

There are other homes, perhaps less grand, but which are just as historic and just as inextricably linked to the job. These are three of them.

The keeper's apartment, Marsh's Library

Dr Muriel McCarthy, keeper at Marsh's Library, can remember only one occasion when a candle was lit in her apartment since her appointment, back in 1989. "And that was only for a few moments." There is no gas in the kitchen, and the old fireplaces have all been boarded up. The naked flame is not a welcome presence in her home.

This is because McCarthy's apartment lies directly underneath Dublin's magnificent Marsh's Library, which was built in 1701 by Archbishop Narcissus Marsh as the first public library in Ireland. The 25,000 books shelved over McCarthy's living quarters are both historic and priceless, because, as a collection, they are irreplaceable.

As well as ecclesiastical books - most of them in Latin - the collection includes books on travel, science, music, navigation and law.

McCarthy, who is the first female keeper, is the first keeper to live in the apartment since the 19th century, so she is the first to live there with electricity.

When the first keepers lived here, the apartment - then twice the size, now split into two separate apartments - was heated by fires. All the cooking was also done over open fires. Luckily, and astonishingly, there was never a chimney fire and the books have never been damaged.

"I'm very conscious of living in a beautiful historic place," McCarthy stresses. "It's a great responsibility." Long before the smoking ban, guests were always asked to smoke outside.

Her two-bedroomed ground-floor apartment has the last Queen Anne style windows in Dublin, and architects often ask to see the antique windows which form part of her plant-filled corridor. One of the previous occupants has inscribed his name on the glass, presumably with a diamond.

There are is a spiral stairs that leads directly from the library to the ground floor, where the apartment is located, so McCarthy need never put up an umbrella on her minute's journey to work.

There is also a separate side-entrance, which leads into a pretty, enclosed garden opposite the apartment, and which is directly overlooked by Kevin Street Garda Station: a fact which adds greatly to the security of the premises.

The library above the apartment these days is cold, in fact, distinctly chilly. It's never heated, as this would affect the books. However, in deference to the comfort of modern readers, the reading room is now heated.

"It used to have a fireplace as well," McCarthy marvels, shuddering at the thought of all those books being exposed to the open flame.

She often walks through the library at night, when everyone has gone home, past all those books in the library's original oak bookcases, including three with cages that people were locked into to read, for fear they would steal the precious books.

"I like to think the other keepers are looking down at me from their portraits, as I carry on their job," she says.

The park superintendent's house, St Stephen's Green

When Éoin McKeon (three) learned how to walk, the first place he wanted to go was to the playground. This would be the preferred destination of many small children. The thing is, the public playground Eoin goes to is virtually in his own garden.

Éoin and his sister Aimee (one) live with their parents, Margaret Gormley and Tom McKeon in the park superintendent's house in St Stephen's Green. Their mother, Margaret Gormley, is the park superintendent for the Green, as well as being responsible for Phoenix Park and the war memorial garden at Islandbridge.

"The park superintendent has always lived in this house. It was designed to be picturesque in the park," Gormley explains. The pretty, red-bricked Queen Anne style house is in the Cuffe Street corner of the Green; a familiar sight for generations of Dubliners who have passed through the park every day. Gormley's post is permanent, and as long as she is in the job, she will live in the house.

The superintendent's house has seen some historic visitors. In 1916, Countess Markievicz commandeered it for a meeting, and asked the daughter of the house to make tea and sandwiches for all. When asked by the then superintendent to whom they should send the bill, the Countess replied, "to the government of Irish Free State".

Gormley has been living in the superintendent's house for 10 years, within the 22 acres which make up what must be the best-loved park in Ireland. "Stephen's Green is a very historical park. By living here, I am living on the job and in the job, and we are part of the local community."

Her office is in the new wooden building a minute's walk from her house: going up the stairs to her office, a picture window on the landing frames the bandstand.

Éoin and Aimee often go to feed the ducks on the ponds and consider the ducks to be their own pets. "They're the best-fed ducks in Dublin!"

Gormley does not tell her children about the nocturnal, four-footed visitor to the Green. It is the vixen who lives in Iveagh Gardens and currently has two cubs. At night, she slinks her way from Iveagh Gardens to the Green, slipping in through the railings, to avail of a takeaway snack.

"It's one way of containing the duck population," Gormley says wryly.

There are currently attempts being made by Iveagh Gardens to feed the urban fox there, so she is not tempted to visit the wildfowl restaurant down the street.

Apart from the privilege of living in a unique address in central Dublin, the family also has the advantage of city-centre parking. "Sometimes, if we are coming home at night and get out of the car to open the Cuffe Street gate, passersby stop to stare at us driving in, and ask us, 'Where are you going?' "

The bishop's palace, Cork

Forget customised number-plates for your car. The real kudos is in having a customised address. The Right Rev Paul Colton, who is Bishop of Cork, Cloyne and Ross, lives in the Palace, Bishop Street, Cork. Previously in a Dublin parish, he was appointed bishop in 1999 and has been in his Cork diocese for six years. The house will be his home until he takes up another appointment or retires: retirement age is 75. Home for himself, wife Susan (a teacher) and twin boys of 11, Adam and Andrew, is the large purpose-built bishop's palace that dates from 1782 and is surrounded by four acres of gardens a few minutes' walk from Patrick Street.

"This is the last of the old palaces in Ireland. Its value lies in the fact that it's still being used for the purpose for which it was built. It has been continuously occupied by a bishop and his family since it was built," Colton explains, pouring coffee in the large ground-floor room which is used both as the formal public sittingroom and by the family as a livingroom.

"For Georgian times, this house would have been considered small, compact and modest," Colton says. The house consists of a a basement, with three floors above. "But only three bedrooms," he qualifies. "The rooms are all big, but there aren't many of them."

For the Colton twins, the best thing about the house is the huge garden and the opportunities for hide and seek. "It's a place of unfettered adventure for them. There is a sense of enormous privilege at living in a place like this. It goes with the job, but it's far from this we grew up, and we do impress on the boys that it is not our house."

There are some disadvantages to living in such a big house that is not theirs. "The colour scheme, for instance, would not always be what we would like. But we have to wait until there is a need for a room to be painted, rather than having it painted just because we would like a new colour."

Very little of their former furniture, which had been bought for a suburban 1970s semi, was suitable for a large Georgian house. And like any large house, renovations are ongoing: at present, work is being carried out on the roof. There are also plans to develop the basement into the diocese's central office. "People have always worked in the basement of this house," Colton points out, "heating water, cooking food. It's appropriate another generation works there, doing a different job."

If the name of Bishop Paul Colton sounds familiar for some reason, think OK! magazine. Yes, that's right. Bishop Paul Colton achieved international fame in 1999 for being the person to marry David Beckham and Victoria Adams at Luttrellstown Castle.

Visitors to the Cork palace who look carefully around them when in the vast entrance hall will notice, along with the twins' sports gear scattered around on various surfaces, a framed photograph of Colton (then a rector) with the Beckhams on their wedding day. "Do I still have contact with them? Ummm. Occasionally," he says, smiling widely.