Five-Minute Memoir: Julia Gregson recalls the moment her war-hero father became a poet

It is Christmas 1980. Snow falls gently on quiet London streets. When my parents arrive early, my husband and I are flying around wrapping presents, making beds and rolling pastry. True to form, my mother looks chic and carefully coiffed.

By contrast, my father wears the periwinkle-blue polyester suit that he brought for $20 in a sale in New Zealand 10 years ago. His family, all women, have been fearlessly frank with him about this suit – he is six foot four and the trousers don't quite cover his long white ankles, or his odd socks. We've tried everything: laughter, threats, but he loves it immoderately. He is carrying his things: book, pipe, shaving kit, brandy, a few old fishing flies, in a plastic bucket. There is also, he says, a poem he's just written. They're early because he's anxious to get the poem to the BBC before they close for the holidays.

I try to keep my expression steady when he says this, but I am secretly horrified. My father, a gentle, self-effacing man, has never done anything like this before, and I imagine trendy young men in pink plastic glasses mocking my father's poem in a bucket, and I feel very protective. Plus, although he has always written, and might have been a writer had the war not made him a fighter pilot, he never changes the ribbon on his terrible old typewriter, which for some reason prints everything in faded italics.

Some of that fear must have shown on my face, for he says: "Don't worry darling – I'm too old to be humiliated," before he takes off: a bent, gaunt LP Hartley figure, walking through snow towards the BBC, the poem now in a brown paper bag.

A couple of hours later he comes back, saying what a nice bunch of young people there were at the BBC party. One of them, a woman called Caroline, gave him a drink, took him off to a side room, read his poem and said she thought it was rather good, and would see what they could do about it. I looked at him sharply. Was this what he would call a leg pull? But he was absolutely serious. "What is the poem about?" I asked. "Hard to describe," he said looking trapped, "about the war and things."

A few months later, my mother calls to say that his poem, The Summer of the Firebird, is to be given a special half-hour programme on the radio. "Half an hour!" I say. "How long is it?" "Five thousand words," she says.

It airs at eight o'clock at night. Martin Jarvis reads the words, the music of Stravinsky's Firebird is its clamorous introduction. My husband and I lie on the bed in the dark to listen.

It is a shattering experience. The poem describes one summer's day in August 1940, when his parachute failed and he got stuck in a tree near Canterbury, burning for 20 minutes before the ambulance came. He was 21. He remembers the incongruously beautiful weather, the smell of flesh burning, the sight of his hands melting like candle wax, and his parade of thoughts – the shame he felt on an earlier mission after finding, inside the wallet of the German he'd shot down, two theatre tickets for that night in Berlin; the memory of kissing my mother, then a 21-year-old WAAF; the grief of losing so many friends, so young. And while he hangs there "babbling and praying" in this tree, waiting for his life to end, a bird in the next tree trills and warbles, blissfully unaware.

Before the poem, I knew what my eyes could see: the stump of a finger burnt off, which he always joked cut short a career as a concert pianist; scars on his neck from the burns which kept him a year in hospital; shrapnel in his heel – but that was about it. Called up at 19, trained in a matter of weeks, strapped into a Spitfire and told to get on with it, he was the product of a system which fined young pilots if they talked about trauma or lost comrades.

The poem changes things between us for the better and forever.

In the 1960s, when I was an adolescent, the Battle of Britain pilots were Pythonesque caricatures: men with fluttering silk scarves and clenched jaws and silly names like Pricky Proud or Sheepy Lamb. I'd joined in the laughter, but forgotten the cost to young men barely old enough to shave, let alone grow a handlebar moustache.

On the night my father died, my sister and I sat up with him. The house was within spitting distance of a beach in Jersey. Shortly before dawn, he started to fiddle impatiently with a tiny, hopeless transistor radio he liked; he sat up in bed and suddenly murmured, "Such fine men", as if seeing them again. It was still dark on the beach, and though he could no longer speak, there were birds to see him out, a family of geese that lived underneath the harbour wall. You could hear them honking, the flurry of their wings, the silky rustle of the tide coming in.

'Jasmine Nights' by Julia Gregson is published by Orion