It must have been in the early hours of the morning when Norah came back into her body and found she had recovered the power to feel. It was almost a physical sensation: it rushed through her veins like a blood-transfusion, like an intravenous drip, and she realised for the first time that her son actually was dead. She had known it, of course, for a good many hours, but now she realised it as well, and the grief that had been quietly waiting for her all this time surged over her, taking her breath away.

Grief for what? For whom? For the broken, damaged travesty of a person that Christopher had become? Or for the bright, precocious little boy, so full of quaint ideas, so passionate for facts, any sort of facts, about anything? A lovely little boy, so strong and handsome and eager, a constant joy to his parents.

A little boy long vanished, and the grief at his loss dissipated, bit by bit, over the long dark years that had followed.

What was left? Staring into the darkness, Norah found herself face to face with the nature of grief itself: not just the strange, ambivalent kind of grief that she herself was experiencing, but any grief, anywhere, for anyone.

Grief, she mused, is like a dark room, intermittently lit by a torch turned this way and that, lighting up one by one all the things that now you need not worry about any more. That long-dreaded telephone call? It has come, it is over, it will never come again. You know the worst now. Never again will you have to lift the receiver, sick with dread lest just this very thing may have happened. It has happened. It can’t happen again. That sudden cry of terror from out in the street? It can’t be your child. Not this time. Not ever again. That shriek of brakes as a lorry thunders by? Nothing to do with you. Not this time.

Christopher not home yet? No longer that nail-biting anxiety – Where is he? – What is he up to? Of course he’s not home yet, how could he be? He’s dead. And then that terrifying article in some medical journal about burnt-out schizophrenics in their forties and fifties; you can forget about that now, for Christopher will never be forty or fifty: never be a burnt-out schizophrenic with no one left to look after him.

No more worries at all. No more fears. No more kidding myself he’s getting better while watching him get worse.

The simultaneous lifting of all these burdens, so vast, so intractable, beyond all counting, was overwhelming. The sensation of weightlessness, for which astronauts undergo months of training, was upon her suddenly, effortlessly, after no training whatsoever, and no relevant skills.

Beyond the heavy folds of the curtains a streaky yellowish dawn was breaking, but Norah did not see it. The distant roar of the awakening city was gathering strength, but Norah did not hear it. She was standing on a high hill, with a confused and distant landscape spread at her feet and a warm wind pulsing in her ears; and at her side stood Christopher. Which Christopher? The eager, promising, lovable little boy? Or the tall and handsome youth with the ruined mind and the sly, too-brilliant eyes?

Somehow, he was both. Tall and handsome, certainly, and yet calling her “Mummy”, as he hadn’t done for years and years and years.

“Look, Mummy! Look! I’m King of the World!” he cried, and with his arms stretched out in triumph and with his fair hair blown by the wind across his forehead, that was exactly what he looked like – King of the World.

She must have slept for several hours, because when she woke it was bright day, the low winter sun almost at its zenith, and the flat was empty.

Well, it would be. The others both had jobs to go to, and though their hours were irregular, they were both usually out for most of the day.

Norah was glad. She didn’t want to face either of them at the moment. Conversation with Diana would be awkward and embarrassing because Diana didn’t know that Christopher was dead. With Bridget it would be embarrassing because she did.

It had been embarrassing already, in fact. When, yesterday, Norah had blurted out the tragic fact, hitherto known only to herself, Bridget had been visibly at a loss. “Oh, God!” you could see her thinking, “What on earth does one say to a bereaved mother? You can’t just say you’re sorry, and walk away … probably the right thing to do is to put your arms around her …” Norah could actually feel the revulsion that had shuddered through her companion at the thought, and she had understood it well. An exchange of duty-hugging between people who aren’t particularly fond of each other can be excruciating. It was awful; and who knew to what heights the embarrassment might have escalated, had not the telephone mercifully intervened.

It didn’t matter who the call was for, or who answered it, for while one was doing so, the other could escape, and so bring the painful session to an end.

An end to the embarrassment, perhaps; but now, looking back on the episode, it dawned on Norah that something more than embarrassment might have been at stake, and she felt stirrings of a new uneasiness.

Why – why – had she been so imprudent as to tell Bridget anything at all of what she knew? She hadn’t planned to do so – hadn’t planned, at that stage, anything at all. In her numbed state she had been acting – when capable of acting at all – entirely on impulse, and the impulse to speak the words “Christopher is dead” had been overwhelmingly strong.

Why so strong? What was it that had provoked so rash and unnecessary a revelation?

Partly, it was Bridget herself who had been the provocation; so self-assured, so well-informed, so jarringly rational in the midst of chaos. She was like a juggernaut, flattening in her path every non-rational consideration, utterly unaware of how they were all leaping back into life behind her as soon as she had passed …

And Bridget’s voice, too. Norah remembered how that voice had gone on, and on, and on, sensible, rational, irrefutable, emphasising key syllables until they rang like hammer-blows through the big, quiet room … on and on and on, uninterrupted, as if she was delivering a lecture; as if this pleasant room with its easy-chairs was a lecture-hall, and Norah herself a whole class of students sitting on benches and hanging on the lecturer’s words of wisdom.

Words of wisdom. Unquestioned Tightness. This was what had provoked Norah, finally, into her ill-considered revelation. For the whole of Bridget’s thesis, so carefully worked out, so clearly presented, so meticulously based on the data so far available – had been completely and ludicrously wrong. The one single bit of data known to Norah but not to Bridget made nonsense of it all, from the first sentence to the last, and the childish impulse to put Bridget in the wrong had been momentarily overwhelming: to put Bridget in the wrong, and at the same time to prove the innocence of her dead son.

All this she had achieved; and it was not until this morning, alone in the silent flat, that she began to realise the implications of what she had done.