'Course you don't,' she'd said with a chuckle. 'But ask yourself this: how many other blokes get into a pretty girl's knickers as part of their job?'

They'd bantered on and off throughout the search. Andrea was a terrible flirt but there was something hugely engaging about the way nothing seemed to faze her, and Bolt was pleased she hadn't taken offence to them turning her house upside down.

There hadn't been any drugs – there hadn't been anything illegal anywhere – and Grindy was in a horrendous mood when they left. 'Cheeky bitch,' he'd complained bitterly. 'You want to keep away from women like her, Mike. They're trouble. Take it from me. I know.'

Grindy had never struck Bolt as an expert on women, but in this case his boss was right. Andrea, however, had definitely got under his skin, and he'd thought about her often afterwards.

It was three years before he saw her again. He was still living in Holborn but had joined the Flying Squad, and was walking down the Strand one afternoon when he heard a woman's voice call out, 'Mr Bolt, are you ignoring me?' He'd turned round to see a woman with jet black hair, a good suntan and big sunglasses coming out of a designer clothes shop. She was dressed in a white sleeveless top, figure-hugging jeans and high heeled black court shoes, and was carrying several bags. There was something familiar about her, the voice especially.

She smiled. 'Plaistow, 1989. My knickers drawer.' Then she removed the sunglasses and it came back to him in an instant.

'Andrea Bailey?'

She shook her head, coming forward. 'No, Andrea Bailey's dead. Meet Andrea Devern.' She put out a manicured hand, and they shook. 'I'm a married woman now,' she added, just in case he hadn't noticed the wedding band and diamond encrusted engagement ring.

'Congratulations. You've dyed your hair.'

She shrugged. 'I fancied a change.'

'It's good to see you again,' he told her, and it was. 'You look well.'

'Thanks. You don't look so bad yourself. Still a copper?'

He nodded. 'Yeah, but not at Holborn any more. I'm in the Flying Squad these days.'

She raised her eyebrows. 'The Sweeney? Very glamorous. So' – she looked around – 'you fancy buying me a drink, or are you too busy?'

Bolt was single at the time. It was a Saturday afternoon and he'd just been wondering about doing a bit of shopping without any real plans.

'Sure,' he answered, 'why not?'

So they'd found a wine bar round the corner, got themselves a nice quiet table and proceeded to demolish a bottle of Chablis.

It was one of those occasions when everything just clicked. They'd only met that one time years earlier, and hardly under ideal circumstances, but even so they talked like old friends. Andrea told him about her upbringing in a council flat, the middle of three daughters brought up by a single mother; how she'd left school at a young age with no qualifications and got herself a job in a local corner shop which she really enjoyed, before a friend turned her on to drugs. 'I got in far too deep, far too fast. Problem was, with my wages, I couldn't pay for them, so my mate told me a great way of earning big money.' She rolled her eyes. 'I was young, and I suppose it seemed like a good idea at the time. I didn't want to work for some pimp, though, so I set up on my own, got business cards printed, and worked through recommendations. I didn't enjoy it, but…' She shrugged. 'It got me money. My idea was to kick the coke, raise a couple of grand and put myself through college. I wanted to do a business course.'

'But you never made it?'

'Oh, I made it all right,' she told him with a smile. 'I kicked the gear, but I took a quicker route to the real money and married it.'

'Always a good move,' he said.

'He's a nice guy,' she told him, her expression suddenly serious. 'He looks after me.'

But on that day at least, Andrea hadn't been in a hurry to get back to him, and with one bottle consumed she'd asked Bolt if he fancied sharing another. He knew it wasn't right to fool around with married women, but he was twenty-four, and the sad truth of the matter was that he was never going to say no.

And so the afternoon drifted lazily on, the conversation veering here and there, covering both their lives. Andrea now lived in Cobham with her husband, a businessman twenty-five years her senior who was, she claimed, one of the nicest guys she'd ever met. 'Present company excepted, of course.'

'Of course,' said Bolt with a smile.

Eventually they got round to how they'd originally met, and with the case of Sir Marcus Dallarda now firmly set in the past, Andrea admitted that she'd been with him that night. 'I'd never met him before but a girl I knew in the business had and she said he was a decent bloke and a good payer, so I went along with her. I never normally did threesomes – I'm not that kind of girl, believe it or not.'

Bolt wasn't sure that he did believe it, but as a trained detective he preferred to listen rather than pass immediate judgement.

'Well,' she continued, 'to cut a long story short, there we were, doing the business, and he conked out. Just like that. Grabbed his chest and keeled over.' Her eyes widened as she recalled the events, and although she was clearly trying to stop herself, a small smile appeared. 'It was comical really, the way it happened. Like something off the TV. I know I shouldn't say that, but it just didn't seem real.

'Anyway, we didn't know what to do. My friend was panicking. She thought we might get the blame for it, especially as he was a bit of a celebrity as well. So I said, let's just get the hell out of here. And that's what we did. But obviously we didn't want him to get found by the cleaner the next day, so we phoned the police and told them. I didn't want to bullshit you when you came round to interview me, but I didn't actually think I was doing anything wrong, you know.' She paused, fixing him with an expression of mild amusement, her eyes twinkling. 'So, what do you think of me now?'

Bolt may have been mildly drunk, but what he thought was that Andrea was a liar. A funny, engaging, attractive and intelligent one, with beautiful twinkling eyes, and loyal too, because she'd never given up her friend, even when he and Grindy had turned her house upside down, but a liar nonetheless, and one who wasn't much good at remembering the details of the past either. Otherwise she would have recalled that the police had originally been led to her by the fact that it was her business card in Sir Marcus's wallet, and not her friend's, meaning that Sir Marcus had almost certainly known her before that night. It seemed a strange lie to tell, given that she'd already admitted that she'd been a prostitute. Why not simply admit that she was the one who'd approached her friend about the threesome, not the other way round?

Not that Bolt said any of this, of course. Instead, he put down his glass and returned her gaze.

'I think,' he said quietly, 'that if I stay here much longer I'll do something I regret.'

'Here's to regrets,' she said, and lifted her glass.

Don't get involved, he told himself. You will regret it.

'You're a married woman, Andrea,' he said, but it sounded lame, even to his own ears.

She sat back in her seat with a wide smile on her face. She was a little drunk too, but her eyes remained sharp and focused. 'Ah, I forgot, I'm talking to a policeman.' She raised her hands in mock surrender. 'All right, you've convinced me. I shouldn't even think about making love to you.'

But it was clear that neither of them was thinking about anything else. Andrea was in London on a weekend shopping trip, and she was staying at a hotel in Bloomsbury on her own. So once they'd finished their second bottle of Chablis Bolt had walked her back. She'd invited him in. This time he hadn't even bothered to resist, and they'd gone to her room and made love before ordering room service, making love again, and finally sinking into the slumber of the drunk and the contented.