The general public have a warped view of the speed at which an investigation proceeds. They like to imagine tense conversations going on behind the venetian blinds and unshaven, but ruggedly handsome, detectives working themselves with single-minded devotion into the bottle and marital breakdown. The truth is that at the end of the day, unless you've generated some sort of lead, you go home and get on with the important things in life - like drinking and sleeping, and if you're lucky, a relationship with the gender and sexual orientation of your choice.

If you just warn people, they often simply ignore you. But if you ask them a question, then they have to think about it. And once they start to think about the consequences, they almost always calm down. Unless they're drunk, of course. Or stoned. Or aged between fourteen and twenty-one. Or Glaswegian.

My dad once told me that the secret to a happy life was never to start something with a girl unless you were willing to follow wherever it led. It's the best piece of advice he has ever given me, and probably the reason I was born.

You put a spell on the dog," I said as we left the house. "Just a small one," said Nightingale. "So magic is real," I said. "Which makes you a...what?" "A wizard." "Like Harry Potter?" Nightingale sighed. "No," he said. "Not like Harry Potter." "In what way?" "I'm not a fictional character," said Nightingale.

The Metropolitan Police Service is still, despite what people think, a working-class organisation and as such rejects totally the notion of an officer class. That is why every newly minted constable, regardless of their educational background, has to spend a two-year probationary period as an ordinary plod on the streets. This is because nothing builds character like being abused, spat at and vomited by members of the public.

Not being invited in is one of the boxes on the “suspicious behavior” bingo form that every copper carries around in their head along with “stupidly overpowerful dog” and being too quick to supply an alibi. Fill all the boxes and you too could win an all-­expenses-paid visit to your local police station.

I gave the prescribed Metropolitan Police "first greeting". "Oi!" I said "What do you think you're doing?