I left the girl my mobile number. The phone account belongs to Noëlle Marcelin, whose identity I acquired some months ago. Her payments are quite up to date – the poor woman died last year, aged ninety-four – but it means that anyone tracing my calls will have some difficulty finding me. My internet account, too, is in her name, and remains fully paid-up. Noëlle is too precious for me to lose. But she will never be my main identity. For a start, I don’t want to be ninety-four. And I’m tired of getting all those advertisements for stair-lifts.

My last public persona was Françoise Lavery, a teacher of English at the Lycée Rousseau in the 11th. Age thirty-two; born in Nantes; married and widowed in the same year to Raoul Lavery, killed in a car crash on the eve of the anniversary – a rather romantic touch, I thought, that explained her faint air of melancholy. A strict vegetarian, rather shy, diligent, but not talented enough to be a threat. All in all, a nice girl – which just goes to show you should never judge by appearances.

Today, however, I’m someone else. Twenty-five thousand euros is no small sum, and there’s always the chance that someone will begin to suspect the truth. Most people don’t – most people wouldn’t notice a crime if it was going on right in front of them – but I haven’t got this far by taking risks, and I’ve found that it’s safer to stay on the move.

So I travel light – a battered leather case and a Sony laptop containing the makings of over a hundred possible identities – and I can be packed, cleaned out, all traces gone in rather less than an afternoon.

That’s how Françoise disappeared. I burnt her papers, correspondence, bank details, notes. I closed all accounts in her name. Books, clothes, furniture and the rest, I gave to the Croix Rouge. It never pays to gather moss.

After that I needed to find myself anew. I booked into a cheap hotel, paid on Amélie’s credit card, changed out of Emma’s clothes and went shopping.

Françoise was a dowdy type; sensible heels and neat chignons. My new persona, however, has a different style. Zozie de l’Alba is her name – she is vaguely foreign, though you might be hard pressed to tell her country of origin. She’s as flamboyant as Françoise was not – wears costume jewellery in her hair; loves bright colours and frivolous shapes; favours bazaars and vintage shops, and would never be seen dead in sensible shoes.

The change was neatly executed. I entered a shop as Françoise Lavery, in a grey twinset and a string of fake pearls. Ten minutes later, I left as someone else.