A gong chimed, a strangely inappropriate sound in the desert.

‘Ten seconds.’

Greg suffered an impulse to get up and run away. Silly though it was – how far could he get in ten seconds? – he had to force himself to lie still.

The bomb went off at five twenty-nine and forty-five seconds.

First there was an awesome flash, impossibly bright, the fiercest glare Greg had ever seen, stronger than the sun.

Then a weird dome of fire seemed to come out of the ground. With terrifying speed it grew monstrously high. It reached the level of the mountains and continued to rise, rapidly dwarfing the peaks.

Greg whispered: ‘Jesus . . .’

The dome morphed into a square. The light was still brighter than noonday, and the distant mountains were so vividly illuminated that Greg could see every fold and crevice and rock.

Then the shape changed again. A pillar appeared below, seeming to push miles into the sky, like the fist of God. The cloud of boiling fire above the pillar spread like an umbrella, until the whole thing looked like a mushroom seven miles tall. The colours in the cloud were hellish orange, green and purple.

Greg was hit by a wave of heat, as if the Almighty had opened a giant oven. At the same moment the bang of the explosion reached his ears like the crack of doom. But that was only the beginning. A noise like supernaturally loud thunder rolled over the desert, drowning all other sound.

The blazing cloud began to diminish but the thunder went on and on, impossibly sustained, until Greg wondered if this was the sound of the end of the world.

At last it faded away, and the mushroom cloud began to disperse.

Greg heard Frank Oppenheimer say: ‘It worked.’

Oppie said: ‘Yes, it worked.’

The two brothers shook hands.

And the world is still here, Greg thought.

But it has been forever changed.

(v)

Lloyd Williams and Daisy went to Hoxton Town Hall on the morning of 26 July to watch the votes being counted.

If Lloyd lost, Daisy was going to break off the engagement.

He fervently denied that she was a political liability, but she knew better. Lloyd’s political enemies made a point of calling her ‘Lady Aberowen’. Voters reacted to her American accent by looking indignant, as if she had no right to take part in British politics. Even Labour Party members treated her differently, asking if she would prefer coffee when they were all drinking tea.

As Lloyd had forecast, she was often able to overcome people’s initial hostility, by being natural and charming, and helping the other women wash up the tea cups. But was that enough? The election results would give the only definite answer.

She was not going to marry him if it meant his giving up his life’s work. He said he was willing to do it, but it was a hopeless foundation for marriage. Daisy shuddered with horror as she imagined him doing some other job, working at a bank or in the civil service, miserably unhappy and trying to pretend it was not her fault. It did not bear thinking about.