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.

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

This is your brain on magic.

Carved above the lintel were the words SCIENTIA POTESTAS EST. Science points east, I wondered? Science is portentous, yes? Science protests too much. Scientific potatoes rule. Had I stumbled on the lair of dangerous plant geneticists?

Conflict resolution,' said Nightingale. 'Is this what they teach at Hendon these days?' 'Yes, sir,' I said. 'But don't worry, they also teach us how to beat people with phone books and the ten best ways to plant evidence.

If you ask any police officer what the worst part of the job is, they will always say breaking bad news to relatives, but this is not the truth. The worst part is staying in the room after you've broken the news, so that you're forced to be there when someone's life disintegrates around them. Some people say it doesn't bother them - such people are not to be trusted.

What's the biggest thing you've zapped with a fireball?' I asked. 'That would be a tiger,'said Nightingale. 'Well don't tell Greenpeace,' I said. 'They're an endagered species.' 'Not that sort of tiger,' said Nightingale. 'A Panzer-kampfwagen sechs Ausf E.' I stared at him. 'You knocked out a Tiger tank with a fireball?' 'Actually I knocked out two,' said Nightingale. 'I have to admit that the first one took three shots, one to disable the tracks, one through the driver's eye slot and one down the commander's hatch - brewed up rather nicely.