Madeleine Andrews was so engrossed in studying her sketchbook that she did not even hear the familiar footsteps on the pavement outside the little house in Camden. When her father let himself in, therefore, she looked up in alarm as if an intruder had just burst upon her. She smiled with relief at the sight of Caleb Andrews, back home from another day as a driver on the London and North West Railway.

'You took me by surprise, Father,' she said.

'It's not often I do that, Maddie,' he said, taking off his coat and cap before hanging them on the back of the door. 'In any case, I'm the one who should be surprised. I was expecting to find the place empty. You were going out with Inspector Colbeck this evening.'

'Robert sent a note to cancel the arrangement.'

'Did he give a reason?'

'He had to go to Cardiff at short notice.'

'That means the Great Western Railway,' said Andrews with a sneer, 'and Brunel's Great Big Mistake of installing a broad gauge. If only he'd had the sense to use a standard gauge on his track, life would be so much simpler for all of us.'

'That's one way of looking at it,' she said.

'It's the only way, Maddie.'

'Mr Brunel would argue that the LNWR and other companies were at fault when they chose a narrower gauge. If everyone else had fallen into line behind him, there'd be no argument.'

'Stop provoking me.'

'I was trying to see it from his point of view.'

'In this house,' he declared, stamping a foot, 'Isambard Kingdom Brunel doesn't have a point of view. I work for a rival company.'