Kitty could feel her resolve to keep her distance slipping away. ‘They wouldn’t have asked us if they hadn’t thought we could contribute something vital. It’s not our fault we aren’t as up to date on how some of our communications were designed – we’re the ones who know how to work them, after all. I’m glad we had the chance to meet some of the people who do a similar job and check we’re all working in the same way. Are you all right?’ she added anxiously, as he continued to rub his temples.

Frank straightened up at once, always sensitive to any implication he was less than one hundred per cent. ‘Of course.’

Kitty sighed, realising he’d assumed she meant his leg, when all she’d intended was to be considerate. ‘Only you look as if you might have a headache,’ she added.

Frank nodded slowly. ‘All right, yes, I have. It’s being cooped up in that stuffy place this morning, and I have to admit I didn’t sleep well last night. Whatever my landlady’s shortcomings, I must confess the bed in my usual billet is extremely comfortable. I’ve been spoilt. The one I was given yesterday had springs poking through it, so I finally slept like a letter Z. Funny, isn’t it, when we spend most of our working lives shut inside an underground bunker, in a warren of small rooms – you’d think this would all be a breath of fresh air.’

‘Well, maybe some air is just what you need,’ Kitty suggested, determined now to be friendly but practical. ‘Come on, we don’t need to get a bus or Underground, we can walk back. I know the way. It’ll do us good.’ She deliberately didn’t ask if he would be all right to walk, knowing it would cause offence and break the fragile truce between them.

Frank tipped his head and looked straight at her. ‘Lead the way then, Kitty. You’re more familiar with this place than I am.’ For a moment she thought he was going to give her his arm, but then he put his hands in his pockets, so she was saved the embarrassment of reaching out only to have the offer taken away.

‘Let’s make our way via the back streets,’ she suggested. ‘It’ll be quieter. High Holborn gets so busy, it will be noisy and do your head no good at all.’

‘Okey doke, as Tommy would say.’

Kitty laughed. ‘I hope he’s all right and not driving your sister round the bend.’

‘How’s that?’ he asked.

‘Oh, you won’t have heard. It was all a bit last minute.’ Kitty found the street she wanted and explained the arrangement she and Sarah had come to, in order not to wound Tommy’s pride but still keep an eye on him.