‘What was it?’

‘Best Rita tells you herself, Sergeant Tennison. It would only be hearsay evidence coming from me.’ He stood back to let her in. ‘I used to be in the police myself, you know,’ he added proudly.

‘In the Met?’

‘No, the Royal Parks Keepers, which became known as the Royal Parks Constabulary in 1974. We trained alongside regular police officers, though, and wore a uniform. We had full powers of arrest and could instigate criminal proceedings for offences committed in the Royal Parks.’

He helped Jane out of her raincoat and hung it up on the hallway coat rack.

‘Are you still serving?’ she asked.

‘I did twenty years, then had to retire after a serious injury on duty. I’m a security guard manager on a big building site now.’

Jane noticed his limp as she followed him to the living room.

‘How did you injure yourself?’

He stopped and turned around before they reached the living room, then started speaking in a formal tone, almost as if he was giving evidence in court.

‘I was night patrol in St James’s Park when I heard a load of quacking at two a.m. I instinctively knew the ducks were distressed and went to investigate, only to discover a man thieving the ducks. On seeing me he started to run, carrying a sack full of ducks in his right hand and one by the neck in his left. I had a torch, but it died on me and there was no moon or park lights, so it was really hard to see. The next thing I knew I ran into a low metal fence, fell over and smashed my right knee to bits on the pavement – it left me with a gammy leg ever since.’

‘Unfortunate way to end your career.’ Jane was trying not to laugh.

‘I got an ill-health pension and a commendation certificate for the suspect’s arrest and saving the ducks,’ he said, beaming.

‘You did well to arrest him with a smashed kneecap.’

‘Thank you, but as luck would have it he fell over the same fence and knocked himself out. He was a little Chinaman and wanted to sell the ducks to a Chinky restaurant in Soho for crispy duck pancakes.’

He sighed, and Jane found it even harder to keep a straight face.

The living room was the same shape and size as the Clarkes’, with similar decor, but not as bright. Rita Brown was sitting on a brown sofa eating a plate of ham, egg and chips covered in HP Sauce. Peter explained the purpose of Jane’s visit and offered her a seat. His own half-eaten tea was on a tray resting precariously on the edge of the armchair. A small Yorkshire terrier was standing on its hind legs with its paws on the armchair, sniffing at the food.

‘Get away, Spud!’ Peter ordered, and the terrier instantly lay down in front of the electric fire.