And together, they stood to hand in hand, stared at the slow progress of time. Until: ‘Lord above, what a spectacle!’ Booker burst out. ‘What on earth are we doing? This is madness. Careering off to the ends of the earth …’

Though the tension was close to unbearable, Mary could not help but smile. ‘Scotland, darling,’ she reproached, with an encouraging nudge and a smile. ‘We are only going to Scotland.’

‘Scotland.’ Booker shuddered. ‘The North Pole, Timbuctoo … They’re all one and the same to me, and that’s the absolute back of beyond of the ends of the earth, if I know my geography.’

But of course: she was terrified! Again, Mary twisted with guilt, for here was another good woman who did not deserve it. She put an arm around Booker’s broad shoulders. ‘You are so brave, dearest.’ She kissed the maid’s cheek. ‘So wonderfully brave and I thank you – thank you – for agreeing to come with me. I could not even think of doing this without you.’

‘As if I had a choice,’ Booker retorted. ‘You can’t do a blind thing without me.’

Mary moved to gather her in a proper embrace. And then it came: the chime of the bells of neighbouring churches. They both froze – counted each strike. And on the ninth, Booker crept to the door – listened to the slumbering silence – and each grabbed their valise.

The maid cast one lingering look at their trunks: ‘You really do trust that mistress to send our things on?’

Mary reassured her again. ‘After this evening, I am convinced of it.’

And, hands enjoined, they tiptoed down the stairs.

It was still only the middle of May, and though the days were now fine, the night was a cold one. Brisk air slapped Mary’s face; her lungs felt close to splitting. Still holding hands, they ran down Great George Street towards St James’s Park, where, at last, Mary pulled Booker in.

‘Here,’ she gasped. ‘Storey’s Gate.’ She clutched at the railings. ‘He definitely said “Storey’s Gate”.’

They hid beneath the branches of a budding magnolia, and peered out. The odd conveyance came trundling past, but all were unhurried and none stopped for them.

‘So where he is then?’ Booker said, as if hopeful. ‘That great lover of yours has changed his mind, has he?’

‘He will come.’ Mary smiled back. She now had her breath back and her spirits were rising. ‘There are still a few minutes to go ’til our rendezvous.’

‘And just suppose he does not, eh?’ Now, she was close to triumphant.

Oh, Mary thought, how you long for that! ‘Then we shall take to our beds and I hereby pledge to unpack both of our trunks before breakfast,’ she replied briskly.