I found a café off the main square which was decorated like a tea shop and served as fine a medley of greasy comestibles as any transport café in the country. Although they did share the regional obsession with providing a lineage for not just your pig but your eggs and potatoes as well. Criminally, I couldn’t tell you what it tasted like on account of the fact that I was practically drumming the table by that point. I was just about to distract myself by calling Beverley when Nightingale called and gave me the go-ahead to collect samples.

‘I know circumstances are fraught,’ said Nightingale. ‘But do try to be discreet.’

I checked my tablet and found I had an email with Walid’s instructions on how he wanted the samples collected, labelled and transported. I don’t need to tell you how important getting a DNA sample from a changeling might be, he wrote. We’d discussed setting up a database of ‘interesting’ DNA samples, but apparently there were legal issues. Patient confidentiality and human rights and all that.

Dominic’s mum had a fully equipped office.

‘From when she thought she was going to run this place as a B&B,’ said Dominic, as he helped me print off the consent forms I was required to get the parties to sign. ‘Do you want me to help?’

‘Your governor doesn’t want you involved,’ I said. ‘Besides, you must have actions piling up back at the nick.’

‘They’ve got me reviewing statements during the initial investigation,’ he said. ‘Occasionally I punch myself in the face to keep awake.’

‘If anything exciting happens, I’ll let you know,’ I said.

To avoid just that, I started with the Marstowes. And, to avoid the posse of photographers at the end of their cu-de-sac, I cut through the adjacent woods, hopped over their back fence and knocked on their kitchen door. Andy answered. He gave me a puzzled look as if trying to work out who the hell I was.

‘You’d better come in,’ he said.

He sat me down in the kitchen and offered me a beer which I declined in favour of a cup of tea. Despite the open window the kitchen was stuffy and there was the starchy overheated smell of baby food. Andy said that Ethan was poorly and that Joanne was upstairs dosing him with Calpol and would be down in a minute.

I asked him for samples and showed him the forms. He asked why and I decided to tell him the truth.

‘If Nicole is not really Nicole, then we should be able to tell by comparing her DNA to her parents,’ I said.

‘I get that,’ he said. ‘Why do you need ours?’

‘In case Hannah was the one that was swapped,’ I said. ‘This saves us having to make two trips to the lab.’

I watched his face as he parsed that and then he chuckled grimly.