He guided her out of the interview room and away from the solicitor. ‘Shireen, I have to say, the moment you provoked him, I was ready. That’s a hot button you pressed, by labelling Aidan a snitch.’

‘I thought it was worth a try.’

‘Next time give me a heads-up before you plan to do it. Right, now on to Aidan.’

Aidan Tickett was held on remand in HMP High Down near Banstead, just a handful of miles from Gillard’s home. Relatively modern, the jail’s interview rooms were light and airy, and Aidan was sitting in one of them by the time Gillard and Shireen arrived. Through the observation window he looked bored, chewing his nails absentmindedly. The paperwork showed his behaviour had been good since arrest. The two police officers went in, accompanied by a female lawyer from Tolliver’s firm. Aidan’s eyes followed Shireen as if he’d never seen a woman before.

Gillard prepped the tape, and began the interview.

‘Now Aidan, you’re being held on—’

‘You accused me of grassing my pa up, didn’t you?’

Gillard was gobsmacked that Aidan had in two hours got word of Shireen’s accusation. He hadn’t even decided how to deal with it before Aidan said. ‘And you’re the bitch that said it.’

Shireen hadn’t managed to get a word out before Gillard decided to suspend the interview. They retreated to the corridor outside to regroup. ‘How on earth did he hear?’ she asked.

‘There are phones in every prison, and if you’re willing to pay enough, you can get contact with whoever you want. But that was very quick,’ Gillard conceded.

‘You don’t think it was the lawyers talking to each other?’

‘Have you ever known a solicitor move that fast? No, I’m pretty sure it wasn’t that.’

They went back in and resumed the interview, but Aidan simply ignored them, saying nothing. After a half-hour, Gillard called proceedings to an end, and after the prisoner was taken away turned to Shireen. ‘Not very informative, was he?’

‘Should we bother with Rory Tickett?’ she asked. ‘Is it worth going all the way to Winchester?’

‘Why not? He was the weak link last time.’

During the two-hour drive to HMP Winchester, Gillard heard about all the paperwork that Shireen had been sent by the SFO’s forensic accounting specialists. They had found duplicate invoices at Aqua Western for much of the work supposedly done by the Tickett contracting firm. ‘That in itself isn’t proof of anything but inefficiency, because most of them were not paid twice. However, the nearest to a smoking gun for Arrowsmith’s involvement is that DCS Anderson’s team found a similar pattern in some of his other work, with different contractors,’ Shireen said.

‘So he’d been doing this before?’