'How singular!' cried Buckmaster. 'Pray, let us see it.'

'Mr Voke forbade me to show it to anyone, sir.'

'But we are not anyone, Mr Kellow – we are friends.'

'Trusted friends, I hope,' said Kate, her appetite whetted. 'What harm is there in letting us have a peep at it? We are very discreet and it is not as if your employer will ever know.'

Hugh Kellow wrestled with his conscience for several minutes, unwilling to open the bag yet not wishing to let them down. He did not wish to spend the rest of a long journey in a strained atmosphere. They had offered him friendship and he needed to respond.

'Very well,' he said, capitulating. 'But you must promise not to touch it.' The others nodded their consent. Kellow undid the straps on the bag and took out an object that was wrapped in muslin. He drew back the folds of the material. 'Here it is – a replica of the Firefly class of 1840, exact in every particular.'

Buckmaster and Kate were astounded. What they were looking at was nothing less than a miniature masterpiece, a scale model that was well over a foot long and that had the substance and sheen of high quality silver. The boiler was fitted to a tall, domed, gleaming firebox. Either side of the two large driving wheels were much smaller carrying wheels. While Buckmaster whistled in amazement, Kate's eyes widened covetously. Kellow was pleased at their reaction.

'The framing has been simplified a little,' he explained, 'and we added some boiler mountings. As for this little embellishment,' he went on, indicating a silver crown at the top of the smokestack, 'it is not mere decoration. It has an important function.' He flicked the crown back on its hinge. 'It keeps the coffee warm before it is poured.'

'It's magnificent,' said Buckmaster. 'I've never seen such fine detail. It must have taken an age to make.'

'It did, sir. Mr Voke is a perfectionist. He worked for an eternity on this commission. He even sent me to Swindon to make some drawings of Firefly locomotives.'