Daisy Mutlar, it must be understood, was someone whom Landen nearly married during our ten-year enforced separation. But that wasn't important. What was important was that without Landen there had never been any Daisy. And if Daisy was around, then Landen must be too—

I looked down at my hand. On my ring finger was ... a ring. A wedding ring. I pulled it forward to the knuckle to reveal a white ridge. It looked as though it had always been there. And if it had—

'Where's Landen now?'

'At his house, I should imagine,' said my mother. 'Are you staying here for supper?'

'Then . . . he's not eradicated?'

She looked confused.

'Good Lord no!'

I narrowed my eyes.

'Then I didn't ever go to Eradications Anonymous?'

'Of course not, darling. You know that myself and Mrs Beatty are the only people who ever attend – and Mrs Beatty is only there to comfort me. What on earth are you talking about? And come back! Where do you—'

I opened the door and was two paces down the garden path when I remembered I had left Friday behind, so went back to get him, found he had got chocolate down his front despite the bib, put his sweatshirt on over his T-shirt, found he had gllbbed down the front of it, got a clean one, changed his nappy and ... no socks.

'What are you doing, darling?' asked my mother as 1 rummaged in the laundry basket.

'It's Landen,' I babbled excitedly, 'he was eradicated and now he's back and it's as though he'd never gone and I want him to meet Friday but Friday is way, way too sticky right now to meet his father.'

'Eradicated? Landen? When?' asked my mother incredulously. 'Are you sure?'

'Isn't that the point about eradication?' I replied, having found six socks, none of them matching. 'No one ever knows. It might surprise you to know that Eradications Anonymous once had forty or more attendees. When I came there were less than ten. You did a wonderful job, Mother. They'd all be really grateful – if only they could remember.'

'Oh!' said my mother in a rare moment of complete clarity. 'Then . . . when eradicatees are brought back it is as if they had never gone. Ergo: the past automatically rewrites itself to take into account the non-eradication.'

'Well, yes – more or less.'