Channel 4 drama explores Mo Mowlam's battle against illness and Northern Ireland's 'dour' politicians. Fionola MeredIth attends a special preview screening at the QFT

Northern Ireland - and in particular its dour, repressed and stodgy male politicans - didn’t know what had hit it, when Mo Mowlam arrived as Northern Ireland Secretary after Labour's election landslide in 1997. She was loud, unflappable, often crude, and forever crushing people to her bosom. Adored by some, resented and despised by others, Mowlam’s larger-than-life personality has sometimes been credited with shaking up the moribund peace process and injecting it with a new energy that ultimately ended in the Good Friday Agreement.

But as this new Channel 4 drama suggests, she was hiding a big secret - one that had serious implications for politics in this country. The brain tumour she was suffering from was not, as she told Tony Blair and the public at large, a benign one. It was malignant, and her doctor had warned her that it could affect her behaviour and her decision-making processes.

When Mowlam (reluctantly) left the job in 1999, her physician, Mark Glaser, felt the professional discomfort of hiding a lie lift from his shoulders. 'I felt nothing but relief that she was no longer doing such an important job, one where, really, anything could have happened. If she'd made an error that had involved a march, or a bomb, how would I have felt?'

So this is a film about the effects of living with a brain tumour as much as it is about Mowlam’s role in the politics of Northern Ireland. That’s just as well, because while Julie Walters excells as the wildly exuberant Mowlam, proficiently steering the character from loudmouth insouciance through to the anger, confusion and eventual silence of her final days, the political dimension of Mo is lacking.

You have to be a little charitable about these things, of course. God knows, the twisted political and cultural convolutions of this place are hard enough for an insider to understand, let alone anyone else.

But it grates when the programme makers resort to a standard compendium of bomb explosions, shards of brick and glass flying through the air, to signal Mowlam’s arrival in Northern Ireland. They include a shot of a man sitting in the back of a hearse, his forehead resting despairingly on a small, white child’s coffin. It’s a common kind of visual shorthand, announcing that the North is (or was then) full of rampaging murderers who don’t stop short at the killing of children. That’s not entirely untrue. But to use those images in such a glib, almost offhand way is both lazy and rather distasteful.

Then there’s the circuitous route that Mowlam apparently takes from the airport to Hillsborough Castle, taking in murals on Sandy Row and the Falls Road on the way. That must have been one expensive taxi ride.

As for our local politicos, some come out a little weedy and wanting. McGuinness and Adams, in particular, are an underwhelming pair. (Someone seems to have told the producers that while loyalists speak in a hectoring, aggressive whine, republicans communicate using a sinister, whispery monotone.) But Adrian Dunbar, as David Trimble, shines, with an unflattering but convincing evocation of the former Ulster Unionist leader, suitably red-faced and irascible.

No, where Mo really works is as a clear-sighted exploration of Mowlam’s own personality, and the possible effects her illness had on it. All the classic Mo moments are here – her bawdy rejoinders, chucking off her wig in the midst of tense political discussions, flashing her knickers at David Trimble (did that really happen? The truth, says Adam Ingram – played beautifully here by Gary Lewis – is much cruder) – but how much of that exuberance was down to disinhibition induced by her condition? It’s a question that Mowlam asks in the film: '[So] good old Mo, larger than life Mo... it could all be because of the tumour? [But] which part's the real me?'

That’s the question this drama leaves hanging. Perhaps it doesn’t matter. Wherever it came from, Mowlam’s irreverent joie-de-vivre both defined her and discombobulated others – with surprising political effects.