PHILIP Gross looks out across the waters of the Severn estuary into a glimmering haze. From where we're standing on Penarth pier, you can usually see Somerset, but today I have to take his word for it: the water meets the sky in a blur of light. He speaks of dramatic 40ft tides, exposing acres of mud flats, and of complex undercurrents which create patches of silk on the surface of the water.
Today, the tide is in, the silt-rich water roiling round the feet of the pier. "Even on a clear day, it's the colour of oxtail soup," he grins.
He smiles and half-apologises for his "obsession with this stretch of water" which inspired his last poetry collection, The Water Table. The book won Britain's biggest poetry award, the TS Eliot Prize, and was described by one critic as "an elegant and subtle re-evaluation of the modern world". It was a rare moment in the spotlight for Gross, 58, an acclaimed writer both for adults and young people for nearly 30 years. Based first in Bristol, now Wales, where he is Professor of Creative Writing at the University of Glamorgan, he has always worked his own territory, off-road from the literary thoroughfare.
"I've not seen myself as a writer who is heavily invested in the ambition business," he says. "There's a lot of quality in the world of writing that no one has time to notice. What has pleased me most is that some people who first noticed this book have then started looking back at previous books and realised that most of the qualities that people so admired in The Water Table have always been there." He has also had a warm response from other writers, those he calls "faithful workers in the field", who got in touch to congratulate him and say: "That's one for all of us." "It's quite reassuring that even people included in that 'all of us' can sometimes appear over that horizon."
Gross is a quiet man with piercing blue eyes. A Quaker for many years, he speaks with thoughtfulness, but relishes the ebb and flow of a good conversation. Ironically, the word which comes up most in our interview is "conversation". Writing is "a conversation", communication with another person is "its natural oxygen". A good poem is one which starts a conversation. "I go quite blank when people talk about writing as self-expression. Why, to whom, and in what context? And which self are we talking about, anyway?"
In the same 12-month period as he won the TS Eliot Prize, he also took the Wales Book of the Year award for I Spy Pinhole Eye, his collaboration with photographer Simon Denison, and his latest book of poems for children, Off-roads to Everywhere, was selected as a Children's Poetry Bookshelf Choice. "It's a bit of the old London bus syndrome. You're standing at the bus stop for years and then three of the darn things come along at the same time. It's been an extraordinary year. I've never been so many places at almost the same time." Next week, he will add St Andrews to that list when he is a guest at the StAnza Poetry Festival.
On the subject of literary success he is equable. "In 30-odd years, I've been serious about my writing through periods of relative recognition and periods when you just need to keep faith that you know what you're doing. There have been enough waves of those that I do recognise them as waves. Hopefully a realistic way of understanding the writing life is that they're tides, they just ebb and flow."
He didn't set out to write a themed collection, he says, it crept up on him. "It did what water does, it seeps its way into every crack. I would think I had been writing about something else and would end up writing about water. I've come to trust to the things you don't know you're doing, the things that creep up on you, more than the ones you intend."
The water in the book is more physical than metaphorical. It flows, trickles, pours into all sorts of subject areas, from the deep past to an imagined future. "Water is a tremendously hospitable medium," says Gross. "Anything can float in or sink in or be dissolved in or be reflected in water. There is lots of thinking about the definitions of things, and that includes ourselves." The estuary before us is itself shifting, between mud and water, England and Wales. Even its name is debatable: it is Severn Sea, Mor Hafren, Bristol Channel, depending on your point of view.
"Having moved over the water from England to Wales, I was very much concerned about, where will I be at home? I think it turns out that I'm drawn to the 'betweenland' in the middle, I don't experience the estuary as a thing which divides nations, but as an opening where the outside world comes in, because that's been my family history (his father was a wartime refugee from Estonia). That's where I feel at home, not in anybody's hinterland."
Gross has a gift of writing poetry which touches both on big themes and on the ordinariness of life, as evidenced by his playful but profound sequence in The Water Table, "Fantasia on a Theme from Ikea". Perhaps unsurprising, it began as a conversation, with fellow poet Jeremy Hooker, whom Gross introduced to the Swedish furniture giant. "He was endearingly horrified, he came out shaking his head, saying 'Nobody could write a poem about that', and I thought, 'OK, then …' I think there's no such thing as a poetic subject. There's a way of looking at things in poetry, but we must be able to look at anything with those eyes. It's how you look. And by that I don't mean looking at things in a fey, whimsical way, but actually looking at what's really there."
It was an interest in the act of seeing that drew him into the project which became I Spy Pinhole Eye, after photographer Simon Denison showed him a series of images taken with a home-made pinhole camera of the concrete bases of electricity pylons. Surely as unpoetic a subject as flat-pack furniture?
"Fantastically unromantic, unaesthetic objects. You think: how can someone take dozens of photographs of those? The extraordinary thing is, it becomes a kind of meditation, and like meditation you find that there's a shift of level, you become as aware of the act of looking as of the thing you're looking at." What he thought would barely stretch to a single poem became an award-winning sequence of poems about the act of seeing.
He makes sure that we also talk about his work for young people, which he considers as important as anything he writes for adults. "I feel quite fierce about that. I think the only good reason to write for young people is that you can be yourself in a genuine way. If I'm writing anything that an adult reader would feel short-changed by or patronised by then I shouldn't be doing it to young people either."
He wrote his first collection of poems for children after reluctantly agreeing to take a workshop in a school in the 1980s, and has never looked back. As his own children grew, he found his writing matched their ages, and he produced several fine, dark novels for teenagers, most recently The Storm Garden (2006) about a girl who falls under the spell of a dangerous young fantasist. "I am interested in the point at which lives go over a dangerous edge. I was increasingly aware that many young people lead lives in which they do come to some kind of harm. Harm is a very real thing."
Gross knew this partly because a story of harm was unfolding in front of his eyes as his teenage daughter was inflicted with severe anorexia. He wrote movingly about his experience of the illness in his poetry book The Wasting Game, a collection of poems which was shortlisted for the Whitbread Prize. Seeing what's really there was a painful process for a father.
His forthcoming collection, Deep Field, to be published by Bloodaxe in November, involves some equally difficult looking, this time at the subject of his own father's old age. A scientist who once spoke five languages fluently, his father has been gradually robbed of language, first by deafness, then severe aphasia.
"Being closely around a person who is undergoing that when you are someone who had formed their life around working with words, it's going to be an affective thing," he says. "It is such a fundamental thing both on a personal level and also because language is where we live. It's arguably where we have selves. If you're off the edge of language, who are you then?
"And yet he is still there. How do you explain that, what he is, what I am, being with each other even so? My experience is that there is something beyond words – or why would you need to do 45 drafts of a poem, why would you get the feeling that is not quite it? What is 'it'? But neither do I think there is a pure and crystalline spirit or soul beyond this mess of matter and language.
"Somewhere in the huge hinterland between those extremes there are probably unanswerable thoughts about who we are, what it means being us at all."
It's particularly hard because, unlike with his daughter, he is unable to ask his father's permission to publish the poems. "I'm dealing with a stage of undignified old age of a kind that he never wanted. I think I handle that indignity in a dignified way, but I'm also being honest. But I think that if he could still grasp what's going on in the language of that book and express his reaction, I think he would approve. As a scientist, he loved what he was studying, but he could study it minutely. I think he would recognise there is an aspect of this in the book."
• Philip Gross is at StAnza's Poetry Centre Stage next Saturday at 8pm in the Byre Theatre, and in an event for children, Off the Road to Everywhere, on Sunday 20 March in the Town Hall Supper Room at 2:30pm. Visit www.stanzapoetry.org