Five o’clock on a bloody Sunday and the roads were packed. Since when was this prime going-out time? As he inched onto the roundabout he could see McDonald’s up ahead. It was heaving.

Ten minutes later he was circling the car park and wondering whether he could stick his car in a disabled spot and use his police pass. The moral dilemma evaporated when a people carrier suddenly lit up ahead of him. A family of five arrived, piled in and were away.

As he prepared to turn into the space, the car in front of him in the queue sounded its horn and reversed towards the spot. It came close to hitting Joe’s front bumper but stopped just in time, leaving it impossible for either car to park. Meanwhile, the driver was gesticulating, mouthing words into his mirror.

‘Twat-face challenge!’ Joe cried out, and had to stifle his laughter before the guy in front saw him.

He and Andy had started playing twat-face challenge as soon as they got into plain clothes. The rules were simple: whenever a situation of boorish arrogance or general twattery arises involving a member of the public, you earn points based on how long you can let it go on without whipping out your warrant card. Deliberate provocation is not allowed; the officer merely has to be polite, tolerant or otherwise passive, preferably until the twat in question auto-explodes in a fit of disbelief.

‘Andy, where are you when I need you!’

Holding his ground and playing innocent was the obvious way to go. So that’s what he did. It didn’t take long. After more sounding of the horn and some aggressive revving from the car in front, the driver’s door flew open and a young man in grey jogging pants came towards Joe, a jaunty spring in his step.

Joe wound down his window.

‘Move the fuckin’ motor, fella,’ the gent said.

He was in his early twenties, no visible tattoos, clean shaven, and had that strangely perceptible aura of someone who is having a lot of sex.

What would Andy Mills say here? This was his absolute favourite kind of twat-face. Then again, Mr Mills had actually been known to cross the road just in case there was an argument worth having on the other side. He simply loved confrontation.

‘Pardon?’ Joe asked.

He could already imagine himself telling Andy over a pint in Whitelock’s. I just said ‘pardon’!

Grey pants tamped down his aggression. He was an edgy, jack-in-the-box type, the tasty fly-weight, the kind of guy who you could imagine working as a bouncer, the skinny one, and everybody thinks the same thing: why’s he working as a bouncer? But everybody knows why.

‘Just back up, will yer, mate? I’ve got mi kid with me, and she’s fuckin’ cryin’ we’ve been here so long. Back it up, fella.’