Grant fairly successfully repressed whatever embarrassment he felt. Suddenly the Baron and Baroness burst out in simultaneous laughter and cries of apology. How ridiculous! How impertinent! Really, what could have possessed them!

Throughout this incident, Major Sweet had contemplated the Van der Veghels with raised eyebrows and a slight snarl. Sophy, stifling a dreadful urge to giggle, found herself observed by Alleyn and Grant, while Lady Braceley turned her huge, deadened lamps from one man to another, eager to respond to whatever mood she might fancy she detected.

Kenneth leant far over the rail and peered into the depths. ‘I’m looking down through the centuries,’ he announced. His voice was distorted as if he spoke into an enormous megaphone. ‘Boom! Boom!’ he shouted and was echoed far below. ‘Ghost beneath: Swear,’ he boomed, and then: ‘Oh God!’ He straightened up and was seen to have turned a sickly white. ‘I’d forgotten,’ he said. ‘I’m allergic to heights. What a revolting place.’

‘Shall we move on?’ said Grant.

Sebastian Mailer led the way to a vestibule where there was the usual shop for postcards, trinkets and colour slides. Here he produced tickets of admission into the lower regions of San Tommaso.

III

The first descent was by way of two flights of stone stairs with a landing between. The air was fresh and dry and smelt only of stone. On the landing was a map of the underground regions and Mailer drew their attention to it. ‘There’s another one down below,’ he said. ‘Later on, some of you may like to explore. You can’t really get lost: if you think you are, keep on going up any stairs you meet and sooner or later you’ll find yourself here. These are very beautiful, aren’t they?’

He drew their attention to two lovely pillars laced about with convolvulus tendrils. ‘Pagan,’ Mr Mailer crooned, ‘gloriously pagan. Uplifted from their harmonious resting place in the Flavian house below. By industrious servants of the Vatican. There are ways and ways of looking at the Church’s appropriations are there not?’

Major Sweet astonished his companions by awarding this remark a snort of endorsement and approval.

Mr Mailer smiled and continued.

‘Before we descend—look, ladies and gentlemen, behind you.’

They turned. In two niches of the opposite wall were terra-cotta sculptures: one a male, ringleted and smiling, the other a tall woman with a broken child in her arms. They were superbly lit from below and seemed to have, at that instant, sprung to life.