I looked closer. The shoebox was full of used tampons. Samantha clapped Babs on the back, and a ripple of mocking laughter went around the captive women. Personally, I thought it was as disgusting as the policemen did, and had to choke back a gag. The smell was unbelievable.

‘Oh for God’s sake, Babs,’ said another officer, climbing out of the bus to see what the furore was. ‘Not again!’ He turned to the young policeman at the desk. ‘She does this every time she’s arrested. Thinks it’s hilarious. Well what I’d say is hilarious is that she has to carry that rank fucking object round with her all day…’

‘You ought to search it, officer,’ said Babs’s companion, putting on a faux-winsome voice. ‘You’d be in terrible trouble if she was smuggling a knife on board, now wouldn’t you?’

To my horror, the constable did actually don latex gloves and have a perfunctory poke around in the contents of the box, his other hand gripping his nose and mouth shut. Our entire queue, plus the queues waiting to get on the neighbouring coaches, hooted with derisive laughter, catcalling and roaring at him. The young copper had gone from white to puce with horror and embarrassment, and I almost … almost … felt sorry for him.

It was horrible on the coach. Freezing cold – I was starting to shiver now, from fear and the chill of recently dried sweat – and with stained velour seats and filthy Formica tables. Three military policemen got on board, one sliding behind the vast steering wheel and two hanging onto metal poles to keep an eye on us all as the engine shuddered into noisy life, the bus’s big windows rattling so hard that I could feel my cheeks vibrating.

One of them, shouting to be heard above the engine noise and the heckling women, made a speech about how we were all arrested and being taken to Reading Police Station, where we would be held until further notice. I looked at Samantha apprehensively.

‘Don’t worry,’ she repeated. ‘It’s going to be fine.’ She held my hand and I gripped hers tightly, unspeakably relieved that she was there.

‘How many times have you been arrested?’ I asked, and she looked skywards, counting off on her fingers.

‘Four,’ she said. ‘And never charged.’

That made me feel a little better.

‘It’s my birthday today,’ I announced, as the coach rumbled through the main gates onto the Newbury Road.

‘Oh WOW!’ said Samantha, kissing my cheek effusively, like we’d known each other for years. ‘Happy birthday, gorgeous girl! Eighteen?’

‘Seventeen,’ I said sheepishly, and she blanched slightly.

‘Jeez. Listen,’ she leaned into me and whispered in my ear, ‘when you’re booked in, for God’s sake don’t tell them you’re underage.’

I was surprised. I’d been planning to milk it, in the hope they’d take pity on me as a child.