It sometimes seems that contemporary poetry divides into two sorts – those poems that did not need to be written and those written out of necessity. Denise Riley belongs to the second category – her writing is perfectly weighted, justifies its existence. It is impossible not to want to “say something back” to each of her poems in recognition of their outstanding quality. Her voice is strong and beautiful – an imperative in itself. But her subject is not strength – it is more that she is robust about frailty. She describes in A Part Song, the most important of her poems, the death of her adult son, Jacob – to whom, along with his sisters, the volume is dedicated.

Maybe; maybe not starts the collection on a wing and prayer – in which Riley refashions the biblical with a new take on Corinthians – I love her line about putting away “plain things for lustrous”. Although written with certainty, it is a poem about doubt, and leads naturally to A Part Song, which follows it. Here she begins by doubting song itself: “You principle of song, what are you for now.” And in song, it is the plain, not the lustrous, she craves. She dismisses the conventional lyrical solace of elegy. “I can’t get sold on reincarnating you/ As those bloody ‘gentle showers of rain’/ Or in ‘fields of ripening grain’ – ooh/ Anodyne.” Instead she wishes her son’s “lighthearted presence, be bodied forth/ Straightforwardly”.

It is a poem of several tones – but never hushed, reverent or docile. This is part of its originality. At one point, she startles with a mum’s scolding tone – painful to read – as she urges her son to be alive almost as you might tell a teenager he has had one sleepover too many and urge him to come home (death the never-over sleepover). And she complains: “But by now/ We’re bored with our unproductive love,/ And infinitely more bored by your staying dead/ Which can hardly interest you much either.”

But it does the poem a disservice to lift individual lines from it because what is remarkable is that it works as an ever-changing, unified and sustained plea to a “strangely unresponsive” son to respond. And then there is the surprise of the ending – a hard-won halt – in which the son’s voice is imagined in two faintly Shakespearean stanzas.

At times, the collection resembles an echo chamber. In Under the answering sky, there is a wonderful line in which she describes what she would like the sky to be and do and say: “… this/ bright flat blue is a mouth/ of the world speaking back”.

There are some first-rate commissioned pieces: Composed underneath Westminster Bridge (a companion piece to Wordsworth), poems about the first world war and its death toll (to which, needless to say, she has no difficulty in relating) and an extraordinary piece about innards (lights – if not light – reading). She is much occupied with questions of animation and lifelessness, the still and restless, the living and the dead. There is a good poem, Tree seen from bed, a never-still life, a restless object lesson in how to be old. There is a fascinating poem about the way inanimate objects console (Lines starting with La Rochefoucauld): “the light constancy/ of things”. And also wonderful is Listening for Lost People where she locates the dead in language itself: “The souls of the dead are the spirit of language:/ you hear them alight inside that spoken thought.” You hear them in Denise Riley’s poetry too.

Say Something Back is published by Picador (£9.99). Click here to buy it for £8.19

Maybe; maybe not

When I was a child I spoke as a thrush, I
thought as a clod, I understood as a stone,
but when I became a man I put away
plain things for lustrous, yet to this day
squat under hooves for kindness where
fetlocks stream with mud – shall I never
get it clear, down in the soily waters.