Isobel groaned. ‘I don’t know. I don’t know what she expects or even wants – but I’m not going to let the poor little boy be used as an emotional football and kicked to and fro across the Atlantic to score points for opposing sides. He’s not just Lorna’s responsibility now – he’s Giles’s too – a little cuckoo in our nest. And that,’ said Isobel, ‘makes it very complicated.’

At that moment they heard footsteps in the hall, the dogs rushed excitedly to the door of the nursery and Giles came in.

‘Good heavens, what on earth are you two doing sitting in the dark? You look like a pair of owls!’ he said. Isobel and Louisa blinked in the unexpected glare as he switched on the lights. ‘Hi there, Louisa. Hope you’ve had a productive day with the writing muse. Hello, my Iz. I’m afraid I’m a bit late, but we got carried away and started on something new. Still we had a wonderful practice.’ As Giles bent to kiss his wife, Louisa watched him touch her cheek with his finger in a small gesture of private intimacy. He gave Isobel a questioning look.

‘You look exhausted, darling . . . you all right?’ he asked.

‘Oh, wonderful, terrific,’ Isobel’s sarcasm was biting. She had been longing for Giles to come home, but at the sight of him the horrible, unwanted feelings of resentment seemed to rise in her gorge like bile. ‘I’ve just been filling Louisa in about our little family dilemmas,’ she said nastily.

‘Oh well, tell the whole world, why don’t you?’ Giles was instantly furious. ‘Louisa can alert our friends and relations to the latest Grant drama and you can announce it to the writing group tomorrow . . . since you made them so interested in the first place.’

Louisa sensed the tension between husband and wife simmering below the surface and felt caught in the cross-fire of matrimonial sniping that might easily ignite into a full-blown fusillade. Perhaps dynamite was not so enviable after all, she thought wryly. Aloud she said: ‘Look, I think I’d better leave you to discuss this in private.’

‘Oh, God! I’m sorry, Louisa.’ Giles was instantly apologetic. ‘That was unfair to you both. I was well out of order.’

Isobel gave herself a little shake as if to dislodge some foreign body. ‘Me too. Sorry, sorry, sorry.’

‘It’s getting late. Bedtime for me anyway I think,’ said Louisa lightly. She kissed her host and hostess a swift goodnight, for once thankful to escape their usually congenial company.

When she had gone, Isobel looked at Giles in horror.

‘What is this doing to us? I didn’t mean to react like that. I could kill Lorna. I feel as if she’s infected me with a horrible virus and my immune system can’t cope with it.’