When I’m thinking of a new story, I usually start with a ‘what if’ question – what if you couldn’t remember parts of your childhood? (Tarnished) ‘What if, sixteen years down the line, you bumped into the man you nearly left your husband for (indeed, your own personal ‘what if’) and you still had that deep chemistry thing going on?’ (Every Vow You Break), or ‘What if your husband died and his lover hung around in your life, claiming in no uncertain terms that you owed her something?’ (Her Husband’s Lover).

About the same time that I’m thinking about that, a setting emerges for me to fixate on. With Tarnished, it was Whitstable/Tankerton, where, at low tide, it is possible to walk right out along The Street – a sand spit stretching a mile into the estuary. When the water is in, you’d have no idea it was there. With Cuckoo, it was the beautifully renovated house of a couple of friends who had nearly finished themselves off by doing it up themselves.

With Her Husband’s Lover, however, I got especially lucky. Not one, but two places wound themselves into my mind – places I had to write about somehow, places that at once reflected and influenced the themes of the book.

The first was a house I passed on a slow train journey from Norwich to Cambridge. The only vertical feature on an otherwise utterly flat, grey fenland landscape, it looked impossibly bleak and lonely. The light from a solitary upstairs floor gave the scene its only colour. I immediately scribbled some notes about who I thought might be in that room. It turned out to be Louisa, one of the two central characters of the book – the Her.

The second – which sees the present-day action of the book – is based on Elephant & Castle in London, where my two adult kids Nel and Owen live in a ninth-floor flat right over the main roundabout. When they moved in about four years ago, the area was in the early stages of a massive redevelopment, which is now in full swing. A major feature of this transformation was the shutting down and demolition of a large council estate across the road from where my kids live – The Heygate.

The estate, once home to more than three thousand people, had, in the noughties, developed something of a reputation for crime, poverty and dilapidation. It is believed in some quarters that the flames of this notoriety were greatly fanned by organisations interested in seeing The Heygate brought down. The scandal doesn’t stop there. Southwark Council sold the land to the developers – Lendlease – for just £50m, having spent £44m on emptying the site and £21.5m on planning the redevelopment. The developers stand to make somewhat more than that.

The Heygate had 1,194 social-rented flats. Elephant Park, which will stand in its place, will provide just 74 such homes.If you wish to buy, you’re looking at £500k for just a studio to north of a million if you want two or three bedrooms. Many of the flats have already been sold off-plan to the Far Eastern investors targeted by the early marketing. The people who used to live there – people who service the city, who drive the buses and Tube trains, who work in the shops, clean the offices, nurse the sick and look after small children – have been priced right out of the area. The displaced residents, if council tenants, were moved to the far reaches of the Borough. If they had exercised their right to buy their flats, they became subject to compulsory purchase orders that didn’t offer enough money to buy again in central London. Many have ended up as far afield as St Albans, Slough and Sidcup. The whole community has been smashed up. It’s hardly surprising that many local people see the redevelopment as a form of social cleansing.

At the same time that I was visiting Nel and Owen and watching these buildings being gutted, peeled and brought crashing to the ground, on the other side of the Thames, the Crossrail project – a 118km new railway line linking east to west right through the middle of town – turned up a Bedlam plague pit from around 1665 at Liverpool Street. The project was stalled while the archaeologists moved in.

This sense of a city constantly changing – be it because of profiteering, disease, war or calamity – became something of an obsession for me. Wherever we walk in a city, we are walking on the dead, and no more so than in central London.

And this layering of history offered the perfect thematic setting for Her Husband’s Lover, which has at its centre a woman trying and failing to re-invent herself, to wipe out her troubled past. Just as the stories and memories of thousands of people who once inhabited a council estate cannot ever be fully erased, the plague dead of Bedlam did not lie undisturbed forever. Everything is unearthed in the end.

And so, while I have Louisa quietly going mad in her past, in her lonely fenland house, I have her re-invented self Lou standing in her 11th-storey flat, shuddering at the thought of the (fictional) unearthed plague pit a few hundred feet away from her window, whilst imagining what it would be like to inhabit the skyscraper that will, in a couple of years, completely obliterate her view.

This is setting at once informing and acting as character, and it makes me a happy writer. Happier, in fact, because I am, in my small way, doing my bit to keep the story of the Heygate alive.

For more about the site, see the excellent and extensive Southwark Notes website