‘Sorry. Sorry. I was here in plenty of time, and I was just used to the routine.’ Mary raised her gaze for a moment, and looked at the reflections of the overhead lights in Nicholls’ black-rimmed glasses. ‘I missed the meeting and I’m sorry.’

Nicholls stopped in front of her and consulted his clipboard. ‘Mary. All staff are required to attend such meetings as management see necessary to facilitate the smooth running—’

He was interrupted by an almighty boom, like someone slamming a heavy steel door. It echoed forever along the tunnel.

When it had faded, he clicked his biro and started again. ‘All staff—’

‘Oh, let’s not worry about that now, Mr Nicholls. Mary’s a good girl and a good worker.’ Mama was in full flow. ‘She’s fine and strong, and she was here early. She’s always on time and never misses a day. She’s one of the best on this team and she said she was sorry and I can tell her what we all talked about while we work, which is what we’re not doing now.’ She turned to the rest of the shift and shooed them into action with her thick fingers. ‘Come on, people. We’re keeping Mr Nicholls waiting.’

Nicholls might have the clipboard, but Mama seemed to run the show.

As the others put their bags down and started on suiting up, the last train was called. It seemed to settle matters, and Nicholls found it necessary to consult the top sheet of the sheaf of paper he had in front of him.

‘Get changed, Noreen,’ was all he said, and went to the locked telephone box on the wall.

Mama waited until their supervisor was otherwise occupied, then took Mary by the elbow.

‘What d’you want to do something stupid like that for, girl? You know he’s just itching for the chance to report you.’

‘I forgot, all right?’

‘Well, don’t you go forgetting again.’ Then she added. ‘Help Mama into her finery, girl.’

Mama was short, but wide, and wore nothing under her boiler suit but a pair of hefty knickers and a bra with more cross-bracing than Tower Bridge. Her wide legs filled the trousers, and she held in the rolls of chocolate-coloured flesh while Mary zipped her up.

‘You’re okay, girl. But you got to pay more attention. Doesn’t matter if you do the job nine times out of ten. Folk like Nicholls, he’s watching for that one time you don’t.’

A waft of hot, steamy air presaged the arrival of the tube train. It rattled and squeaked into view, and the carriages flashed by. Then it slowed, and the blur of windows resolved into discrete images of people mostly standing, even though there were plenty of empty seats.