Nearly two decades in the business, despite her tender years, and Melissa has seen it all. There was the staff member who went onto the tracks at Biggleswade just after being dismissed for drunkenness, the man who leapt off the bridge at Newark and grabbed the overhead wire – he survived, despite suffering what were euphemistically referred to as life-changing injuries. A week after that, Melissa exited her office here in Peterborough just in time to see a hen party of six young women stagger onto Platform One for a London train, two of them clutching bunches of pink helium balloons with very long strings. ‘Pull those balloons down now!’ she shouted at them, so loudly that the other customers and staff on the platform turned to look. She strode up to the women and addressed the bride-to-be, who was wearing a pink satin cocktail dress, a white veil and purple Dr Martens. ‘What do you think those things are made of?’ Melissa snapped at her. ‘Aluminium! It’s metal! Metal conducts electricity!’

As she turned away, she heard the young women titter, then one of them say, loudly, ‘Fucking fun police out in force today, girls.’ The voice was daring Melissa to turn and remonstrate. The young women all laughed false, horsey sort of laughs and Melissa went into her office and closed the door behind her. She sat at her desk and put her head in her hands, thinking of the moment the young man had leapt from the bridge at Newark, right in front of her, his mouth wide open as his hand reached out for the over-head wire. The flash; the shock on the faces of the people waiting on the platform below; the way an elderly woman had said to her, as the ambulance pulled away outside the station, ‘That young man will be alright, won’t he? Why didn’t you stop him?’

Paramedics, police officers, firefighters – well, they might deal with emergencies more often but rail staff do it too and then half an hour later they have to explain to a First Class passenger just how sorry they are that their menu choice on the meal service is unavailable. Sometimes Melissa wishes she had just gone on that course to be airline cabin crew. At least passengers on aeroplanes understood the relationship between their chosen mode of travel and sudden death.

Melissa is about to leave her office – she’s actually reaching for the door handle – when the phone on her desk rings. Against her better judgement, she picks it up and is immediately sorry she did.

‘Melissa! I’m so lucky to have caught you …’