Jane decided to return to the office and tell Kingston what she’d learnt from Rita Brown. En route she dropped in to Leytonstone Police Station to collect the house-to-house folder and spoke to the duty sergeant. He informed her that all the flats in Edgar House had been visited, as well as the houses in Blake Hall Road and the first six houses on either side of Felstead Road. He had also debriefed the officers who made the enquiries, and no one reported seeing anything of interest to the investigation.

It was 7 p.m. when Jane got back to Rigg Approach and parked her VW in the street outside the squad offices. She couldn’t remember the key code, and was flustered for a moment, until she remembered to look in the back of her pocket notebook and quickly entered 1066 to open the door. Upstairs the squad room was empty. She knocked on Kingston’s office door, but there was no reply. She knocked again, but still there was no answer, so she opened the door and peeked in, but he wasn’t there, though his jacket was over the back of his chair. She then tried DCI Murphy’s office, only to find it empty as well.

Having seen Kingston’s jacket on the chair, Jane wondered if he might be in the gym working out and decided to go down to the basement to see. As she got near the locker room she could hear a male voice grunting and the rhythmic sound of squeaking metal from gym equipment being used. She entered the locker room and was about to say, ‘Excuse me, Guv’, when the sight that greeted her froze her to the spot.

Kingston was standing with his back to the door and his trousers down by his ankles, while Katie knelt in front of him on a weightlifting bench that rocked and squeaked in time to Kingston’s thrusts.

Jane was no prude, but this was a situation she didn’t want to get caught up in. She’d never in her life seen another couple having sex, apart from a brief glimpse of a porn movie she’d caught her male colleagues watching in the snooker room on night duty when she was a probationer at Hackney. Thankful she hadn’t disturbed them, Jane crept back up the stairs as quickly as she could and grabbed her coat and shoulder bag, but as she went out of the office onto the landing she could hear Kingston and Katie talking as they walked back up the stairs. She darted into the ladies’ toilet across the hallway and sat down to wait for their voices to subside so she could sneak out to her car. She recalled DC Lloyd Johnson saying Katie liked attention and got plenty of it from Kingston, but she’d never imagined they were in a relationship. She heard Katie’s voice just outside the toilet.