‘You weren’t here when I first arrived, sir, and DI Kingston told me to go with him to the robbery in Leytonstone. Then I was dealing with the scene where the police car crashed and the burnt-out car—’

‘That’s obvious from the soot on your blouse. I’ll let it go this time, but in future if you have a meeting with me I expect you to be there on the dot – or waiting for me if I’m running late. Take a seat.’

She sat down opposite him while he topped up his glass from the whisky bottle, then screwed the cap back on and put the bottle in his desk drawer.

‘Do you know much about the Flying Squad?’

He took a sip of his drink and leant back in his chair.

Jane thought for a moment. ‘It was formed in 1919 in response to growing concern about organised crime in London and the unit’s original twelve detectives could pursue criminals into any police division area, hence the nickname “the Flying Squad”. Over the years, the unit became primarily involved in preventing and investigating armed robbery and organised crime. Currently there are four squad offices in London, based here, Barnes, Finchley and Tower Bridge.’

Murphy yawned. ‘Ten out of ten if you were writing a history essay, Tennison, but what I meant was do you know what we do on a daily basis?’

Jane wondered if Murphy was deliberately trying to catch her out by not making his question very specific. She tried again, being as precise as she could.

‘From what I was told, the Flying Squad carries out surveillance on criminals it suspects may be about to commit armed robbery on business premises, banks and betting shops, then arrests the suspects before the commission of the crime. The squad also investigates offences already committed by armed robbers on the aforementioned premises.’

Murphy frowned. ‘Basically correct. Flying Squad operations generally start with lengthy surveillance, followed by armed intervention and an arrest for conspiracy to rob prior to the offence being committed. That way Joe Public is safe from flying bullets and no one gets shot – not even the bloody suspects . . . unfortunately.’

‘Isn’t that a good thing, sir?’ she asked, remembering the first thing she’d had drummed into her at Hendon training college, that the primary object of the police was the prevention of crime and the protection of life.

Murphy sighed and shook his head, as if she’d said something stupid.