John supped deeply on his pint, sat back in his seat and sighed. ‘Well, there are three types. The first one explodes on landing, the second has a thirty-minute timer and the third explodes five seconds after the slightest disturbance.’

‘Oh dear, what was this one?’

‘Simply one that misfired – so not too dangerous.’

‘If you know what you’re doing,’ added Tom with a wry smile.

‘And why is it called a butterfly bomb?’ asked Lily.

John gripped his pint tankard and stared into his beer. ‘It doesn’t look like a conventional bomb, not like a rocket with fins. It has a cast-iron cylindrical body about the size of a baked bean tin. Then they’re covered with a pair of curved flaps that resemble a butterfly’s wings.’

‘But that would attract children – just like David and Malcolm,’ said Lily.

‘Yes, they were often brightly coloured for that reason. However, this one was worn with age and simply looked like a rusty can.’

‘That’s horrific!’ said Lily.

‘That’s war,’ murmured Tom.

There was silence while the enormity soaked into Lily’s consciousness.

John lowered his voice. ‘The Germans used them to bomb Cleethorpes and Grimsby. They dropped dozens of them in a container from an aircraft. At a pre-set height they all fell out, then the force of the rushing air opened up the wings. After that they revolved like sycamore keys and floated to the ground while a turning screw activated the bomb. Inside there’s about four and a half pounds of high explosive.’ He took another drink of beer and looked down at the tabletop. ‘The killing radius is about eighty feet.’

‘I heard they were almost impossible to diffuse,’ said Tom.

‘Yes, it was difficult,’ agreed John. ‘So we made sure the whole town was closed down and there was a news blackout. We didn’t want the Germans to be aware of the dreadful impact of this kind of bombardment.’

For a while they sat in silence until, after Tom had bought another round of drinks, they relaxed.

Lily looked at her wristwatch. ‘Millicent Merryweather offered me a lift.’ She stared out of the window at the darkness beyond. ‘I shall have to telephone her. I don’t want to cycle back in the dark.’

‘I can take both of you back home,’ said Tom. ‘It’s the least I can do.’

John looked across at Lily, a hint of disappointment on his face. ‘That’s kind, Tom, but I can walk – and one day I may own a car of my own,’ he added with a forced smile.

The three left together, each with their own thoughts.