A mother is wronged by the Catholic Church in this surprisingly uplifting feature shot in County Down

Given the track record of similarly-themed dramas, there is an initial fear – both for one’s own mood and for the wellbeing of the characters on screen – that Philomena is likely to be a bit depressing.

2002’s The Magdelene Sisters was a cold and brutal film focusing on the fates of young Irish girls despatched to grim convents to repent for their ‘sins’, be they pregnancy out of wedlock, 'loose morals' or other.

Fortunately, however, Stephen Frears' film is a far breezier affair. The spectre of the Catholic Church’s less salubrious practices may linger ominously in the background – the villain of the piece, if there is one at all – but this is mercifully offset by winning performances, a terrific script and a variety of scenery very much at odds with the chilled claustrophobia of the austere nunnery.

Based on former BBC news reporter and Labour Party spin doctor Martin Sixsmith’s book of the same title, this film recounts the journey taken by Sixsmith in assisting retired Irish nurse Philomena Lee to look for the son taken from her in the early 1950s.

As a resident/inmate of the Sisters of Mercy convent in Roscrea, County Tipperary, the teenage Philomena had no choice but to waive the parental rights to her young son Anthony. She could only watch as he was sold into adoption. Her search for him would begin after leaving the institution, proving fruitless until the time of Anthony's 50th birthday and her unlikely alliance with Sixsmith.

It is to Sixsmith’s credit in the source material that he paints himself as neither hero nor crusader. If anything, his involvement in the story owes more to boredom and his eagerness to re-establish a career – after spinning himself out of a job – than it does to his strong moral compass. In reality, Sixsmith’s character is that of a pompous, sarcastic know-it-all, bestowing his benevolence on one of the little people.

Steve Coogan’s ease with the role is quite fitting then, having already appeared this year as a superficially charming Englishman in the excellent What Maisie Knew. Coogan has made a career of playing this kind of morally ambiguous figure, and his work as co-writer of the screenplay is evident in Sixsmith’s clever wit and mildly snide asides.

First encountered as a newly unemployed spin doctor, following an unexpected sacking, Coogan deftly conveys an unspoken mix of wounded pride and self-righteous anger in his portrayal of Sixsmith, out of a job he enjoyed for failures he believes are not his own. Beyond jogging and ‘writing a book on Russian history’, his plans are fairly vague, and he champions Philomena’s cause slowly and, at times, reluctantly.

Yet it is in the face of hypocrisy, secrecy and an increasingly compelling story that his instincts come alive. Spurred on by his spiky editor (Game of Thrones star Michelle Fairley) to get the juiciest story possible, he comes to realise that this is a tale worth telling.

Sixsmith’s lapsed Catholicism allows a certain level of insider knowledge when faced with the same quiet recalcitrance that Philomena has come to expect, even if it is presented with buttered brack and a smile instead of a scowl, a blouse instead of a habit.

His relationship with Philomena is crucial and through Judi Dench, the title role is filled out – and then some. What could have been a simple characterisation of an emotionally damaged woman is infused with energy and a deadpan comedic streak that ensures her lines are the best ones. For all the cruelties she has suffered, Philomena remains a hopeful person, her faith intact.

It is a layered and accomplished performance, and when describing the circumstances of her pregnancy, or the reasons for gay men eschewing contraception, there are laughs aplenty in the frankness of Dench's delivery. One standout scene involves her discussing, at length, the plot of her latest Mills & Boon. She even gets to make a Ryanair gag.

Rostrevor and the stunning south Down landscape fill in ably for Roscrea and the Tipperary countryside. Northern Ireland is not the only location to serve the film, however. Philomena’s search would take her across the Atlantic also, from the low key civility of London to Washington DC and rural Maryland.

As they move from place to place, an understanding is reached. Martin and Philomena come to recognise each other’s necessity to the final outcome, whether as a central player in a ‘human interest story’ or as the man with the guile and skill to access the truth.

If there is one flaw it is that Philomena vacillates between serious drama and light comedy. It never appears to settle on either, with the more sombre moments occasionally undercut by a throwaway quip, however amusing it may be. Such moments are not liable to ruin the film’s ultimate effect, but they can be a jarring reminder of Coogan’s comedy roots.

There is courage though in presenting a film about Catholic Church malfeasance and lost children as something other than the dark and distressing studies seen before now. Yes, the story is true but its message of forgiveness is a surprisingly original one considering the subject matter. Don’t be surprised if this is in the running come awards season.

Philomena runs in Queen's Film Theatre, Belfast until November 14.