‘I’ll leave you to it,’ Andy whispered, and headed off.

The cyclist, dressed in jeans, newish trainers and a maroon cotton hooded sweatshirt, slowed as he approached the tattered remnants of the crime scene tape, and stopped by the flowery hillock adjacent to the path. Blake stared away, but followed him in his peripheral vision, while muttering to himself angrily in what he imagined to be a convincing Glaswegian accent. He reckoned he’d be up for a BAFTA for this.

The man got off his bike, set it down carefully, and made his way across to the edge of the flowers. He seemed to be reading the various cards and flower labels. After a few minutes, he stood up, took a quick glance in Blake’s direction then headed off further to the edge of the woods. Blake had already taken a quick photograph of the bike when the man’s back had been turned, and now took the opportunity to make a video of him as he poked about in the shrubs just ten feet or so from where the murder took place. The man cast a couple more furtive glances behind him, and moved further into the woodland. He was definitely looking for something.

After a couple more minutes, it was clear he hadn’t found it, and made his way gradually back towards his bicycle. The plainclothes officer was draped drunkenly across the bench, his mouth partially open. But he still took in the man’s quick smile of complicity, as he picked up the bicycle, turned it around and wobbled off back in the direction he had come.

Prisha Roy and Simon Parr-Fielding lived in a large modern detached home on the edge of St Albans. There was an extensive well-kept garden with a large rhododendron hedge, and a treble garage outside which was parked, with some incongruity, an old and rusty VW camper van with two hubcaps missing. As DI Claire Mulholland edged in her unmarked Ford Focus, she turned to DC Michelle Tsu. ‘No sign of her ladyship’s Porsche Cayenne. If she is out that might make things easier.’

They parked, made their way up to the front door and rang the bell. Pop music was playing loudly inside. After three tries on the buzzer and an extended wait, a middle-aged man opened the door, glass in hand. He was in denim shorts, an untucked white cotton shirt and flip-flops. The detectives introduced themselves and then asked: ‘Mr Simon Parr-Fielding? We’d like to ask a few questions if we may.’

He shrugged and led them in to an equatorial heat, before offering them drinks: ‘I make a good mojito if you’re interested.’ They settled for coffee, but it arrived served in a glass with a mountain of aerosol cream on top. ‘I take it you’re going to pass on the brandy? I also find it goes rather well.’

They waited for him to arrange himself on the leather settee, one leg over the arm, and one arm behind his head. ‘So, how can I help?’