She indicated the price and Alex produced his card. The videos vanished and reappeared safely wrapped.

Luckily, Bobby had started bickering with Mitzi and noticed nothing.

‘How about something to eat?’ Alex asked. All this undercover work was exhausting.

They found a café and Alex studied the menu, but the other two knew what they wanted.

‘Cocoa and cream buns,’ Mitzi said blissfully.

‘Yes, please,’ Bobby chimed in at once.

‘But what about your lunch?’ Alex objected. ‘If I take you home already full your mother will kill me.’

‘It’s real cream,’ Bobby pointed out.

‘Lots and lots of it,’ Mitzi said ecstatically.

‘Does Mummy allow you to eat cream buns before lunch?’

They considered.

‘No,’ Bobby said regretfully.

‘No,’ Mitzi agreed.

‘Well, then!’

Bobby regarded him innocently. ‘But Mummy isn’t here.’

Alex made the mistake of engaging him in debate.

‘But aren’t you equally bound by her rules even when she’s absent?’

‘No,’ Bobby explained. ‘Because it’s Christmas, so she might have changed her mind, just this once. We don’t know, do we?’

‘I suppose we don’t,’ Alex said, eyeing his son with new respect. ‘Mind you, I’ve got my phone. We could call and ask her.’

‘That wouldn’t be fair,’ Bobby said quickly. ‘Mummy’s very busy, doing last-minute things. We shouldn’t interrupt her.’

‘Ah!’ Alex gave this idea his full attention. ‘You think we could simply assume her agreement-out of consideration for her?’

‘Yes,’ Bobby said firmly.

They shook hands.

‘When you want a job,’ Alex told him, ‘come to your old man. The thought of you arguing on the other side scares me stiff. You’ve got every trick.’