New light was shed yesterday on Kingsley Amis, one of the bestselling English novelists of the last half-century, by a freshly discovered poem so confessional he apparently never showed it to anyone.

The untitled poem has been found among his 68 boxes of posthumous papers at an American university. Its existence was unknown to his family, close friends, or agent.

The man who uncovered it, Amis's biographer, Professor Zachary Leader, said: "It has power from first line to last."

He told the Guardian he was surprised to find the author, who was nicknamed "the old devil" after the title of his Booker prize-winning novel, getting up early to walk in the garden and wanting his work to serve "another's good".

Last night Amis's son Martin said: "I feel it is one of his best because it is very unguarded, undefended by irony."

Amis was viewed by his literary enemies - and much of the media - as a lethargic curmudgeon who drank too much and would have dismissed such sentiments as bogus. But Prof Leader said he also possessed seriousness, intelligence and generosity of spirit.

He said the verse, provisionally entitled Things Tell Less and Less, had "a more powerful directness and despair, unmediated by humour" than his other poems.

Evidence suggests it was written in the late 1970s when Amis was nearing 60. As a view of late middle age, it emerges as a startling companion poem to his friend Philip Larkin's desolate poem Aubade, written in the same period.

Larkin wrote of waiting in bed for dawn:

Till then I see what's really always there:
Unresting death, a whole day nearer now,
Making all thought impossible but how
And where and when I shall myself die.

But Larkin published his poem while Amis, who was usually more extrovert, did not.

"I think it was the confessional character of the work which stopped him," Prof Leader said.

Untitled

Things tell less and less:
The news impersonal
And from afar; no book
Worth wrenching off the shelf.
Liquor brings dizziness
And food discomfort; all
Music sounds thin and tired,
And what picture could earn a look?
The self drowses in the self
Beyond hope of a visitor.
Desire and those desired
Fade, and no matter:
Memories in decay
Annihilate the day.
There once was an answer:
Up at the stroke of seven,
A turn round the garden
(Breathing deep and slow),
Then work, never mind what,
How small, provided that
It serves another's good
But once is long ago
And, tell me, how could
Such an answer be less than wrong,
Be right all along?
Vain echoes, desist

Kingsley Amis