I looked back and saw that Guleed was talking to a young Chinese guy in a purple open necked shirt, pre-faded jeans and leather trainers. He was short but broad-shouldered, his black hair cut with a long fringe. In his left hand, as if glued in place, he carried a slim bamboo and leather case which I couldn’t definitely identify as a sword scabbard only because of the blue drawstring pouch covering the pommel.

He leaned forward like a bird dipping for fish and said something that made Guleed laugh. I saw her eyes flick in my direction and so did his. He turned to look at me, grinned, and gave me a polite nod and a mocking salute before turning and walking away.

‘That was interesting,’ said Guleed when she joined me. She showed me his card. It was expensive in its simplicity, a good card stock and superior printing. It read MICHAEL CHEUNG in black ink and, in smaller print underneath – LEGENDARY SWORDSMAN, and under that two clusters of Chinese characters. Guleed was reluctant to hand over the card, so I took a picture to send to Postmartin for translation and analysis.

‘He said that he was the new guy in Chinatown,’ said Guleed. ‘And when you had a moment he’d like you guys to drop in at the usual place for dinner. He said Nightingale would know which place.’

‘And it took him ten minutes to say that?’

‘He also gave me his phone number,’ she said.

‘You going to call him?’

‘Probably,’ said Guleed.

‘And if he draws that sword, are you going to arrest him?’

‘That depends, doesn’t it,’ said Guleed. ‘On what he does with it.’

Which was Guleed for ‘mind your own business’, but I might have pursued the matter just a little bit further in the interest of intra-collegial due diligence if the manageress of The Chestnut Tree hadn’t chosen that moment to come back from lunch.

She was a white woman in her late thirties with an oval face atop a rather long neck which she grew her light brown hair long enough to partially disguise. She was wearing a no-nonsense, easy to clean, light pink blouse with black jeans and nice comfortable flat shoes. Her eyes were light brown, but even before I got close enough to see the flecks of hazel-gold around the iris I had her pegged as being fayer than the client list of a New Zealand casting agency.

Her name was Wanda Pourier and she had the kind of Estuary accent that says she could have grown up in London, only her parents moved to the Thames Valley when she was young – presumably to find work in the boredom mines.

‘We’d better talk in my office,’ she said. ‘We don’t want you lot scaring the punters more than you have already.’