Mr Loverman review: Lennie James's powerful performance means BBC1's new drama ranks with the year's best

Barrington Walker will not – at his advanced stage in life – “make you explode, just like a bomb”, but he is on the verge of detonation.

That's because Barrington – played with a quivering conviction by Lennie James – is hiding a deep, dark secret; a secret he's kept from his family for decades.

Based on a novel by Bernardine Evaristo, Mr Loverman tells how Barrington – mid-70s, married to Carmel, two daughters – is ready to put a bomb under his marriage and reveal how he has been conducting a long-running affair.

Not something we haven't seen before, you might think, but Barrington's affair is with Morris – to all their family and friends, simply 'Uncle Morris'.

But for Barrington, Morris is a long-suffering partner, a soulmate, a lover.

And he's willing to give up the security of family life, and possibly lose his children and grandson, to finally live with Morris and live out the rest of their days together.

The problem is, Barrington has said this before, and always found an excuse not to do it. Over decades, he has transferred his fear and cowardice on to his wife, so now the accumulated bile and bitterness towards Carmel (Sharon D Clarke) burns and burns, giving him perpetual heartburn whenever Carmel is in the room.

He resents her for his own failures, his own lies, his own refusal to face the truth of his own life.

Barrington could be an unsympathetic character, but in James's eyes you can see the longing he has for Morris, the longing he has to be the mum he's always wanted to be and live the life he's always wanted to have.

And the relationship between Morris and Barrington is so sharply drawn, and beautifully played, that you can't help rooting for them.

Meanwhile, at every turn you are aware of the incredible hurt that would ensue for Carmel and their two daughters, Donna and Maxine, should Barrington leave them.

Clarke is exceptional as the bewildered Carmel, wondering how her marriage has soured, not understanding the reasons for it.

There's a beautiful scene as Barrington drives Carmel to the airport, where she's getting a flight back to Antigua to look after her sick father; a scene full of regret and love.

“What happened to us Barry?” asks Carmel.

“Life happened to us.”

Meanwhile, that life is played out in short flashbacks, giving us glimpses of their lives as young people back in Antigua, the lives they built when they emigrated to London, and the lives of the people around them.

There are times when it's a little theatrical, a little stagey for a television show.

In the first episode there's an extended scene around the kitchen table, Barrington fuming as Carmel and her church friends pontificate about the evils of homosexuality.

While in the second, a scene in a cafe between Barrington, his younger daughter Maxine and Morris could have come straight off a stage.

And there are some lines which could have come from a Facebook meme or a fridge magnet.

“Some people don't get a chance in life, let alone live it the way the want.” says Morris.

But the performances, the energy, and the wit in the script make up for any deficiencies, and split into bite-sized, 30-minute chunks, it's one of those shows where you sit down to watch one episode, and find yourself there two hours later, still hooked.