There were still a couple of phone boxes on the High Street. Most of them had been swept away by the popularity of mobile phones, but a few remained. One of the two was out of order. I went into the other one, looked around to see if anyone was watching, and dialled the first landline number, designated in Mel’s phone as ‘BW’. The phone booth was grimy and cigarette-burned and stank of stale piss, but I didn’t mind too much; in a strange sort of way it was almost reassuring to find that some things hadn’t changed since my youth. The number rang three times before a female voice picked up.

‘Hello, CEO’s office, how can I help you?’

‘Oh, sorry, think I might have the wrong number, who have I called?’

‘Zero One Zero Limited, sir. Can I help you?’

I hung up. Ben’s company.

The next number in the list was marked ‘W’. Mel’s secretary, Gavin, picked up after one ring.

‘W’ was her work number, her direct line. That seemed a bit weird – why would you have your work number on an illicit mobile phone? I hung up without a word. Stared at the phone for a second, then redialled. Gavin answered again, giving the exact same greeting.

‘Hi,’ I said, trying to raise my voice half an octave. ‘Could you put me through to Melissa Lynch, please?’

‘Who’s calling?’

I looked across the street. A Burger King.

‘Mr King.’

‘Will she know what it’s concerning?’

‘Yes, I’m sure she will.’

He put me on hold and came back half a minute later.

‘I’m afraid Mrs Lynch is out seeing clients this morning, Mr King. She should be back about 3 p.m. Can I take a message?’

I hung up. It struck me again how little I knew about her day-to-day work, her movements and who she was with at any given time. And in that context, the work number also made sense – because it would allow her to co-ordinate absences from the office, make excuses, call in with a bogus appointment here and a fictitious client conference there when she had an opportunity to spend time with Ben. Pieces of the puzzle were starting to fit together: this was how you used new technology to conceal the oldest of sins.

It wasn’t warm in the booth, but sweat was already making my shirt stick to my back. The next number rang three times before a young female voice answered. Home Counties accent, confident, posh.

‘Good afternoon, Pollard and Clarke, how may I help you?’

‘Hi, sorry, who have I called?’

‘Pollard and Clarke, sir. How can I help?’

‘Oh. What exactly do you do?’

‘We offer a range of legal services, sir, what’s your particular requirement?’