During the 1990s, when the architect who built this place had been commissioned, he had been told that he was designing luxury apartments for thrusting young professionals. No doubt he envisioned power suits, braces and people who would furnish their home with the bleak minimalist style of a Scandinavian detective novel. In his worst nightmare he probably never considered the idea that the owner would use the generous proportions of the living room as an excuse to cram in at least four World of Leather three-piece suites. Not to mention a plasma television, currently showing football with the mute on, and a huge plant in a pot, which I recognised with a start as being a mangrove tree. An actual mangrove tree, whose knobbly-kneed roots spilled over the edges of the pot and had gone questing through the shagpile carpet. I looked up and saw that the topmost branches had thrust up through the ceiling. I could see where the white plaster had flaked away to reveal the pine joists.

Arrayed on a leather sofa was as fine a collection of middle-aged African women as you’d find in a Pentecostal church, all of whom gave me the same once-over that Beverley had. Seated incongruously among them was a skinny white woman in a pink cashmere twinset and pearls, looking as perfectly at home as if she’d wandered in on her way into town and had never left. I noticed that the heat wasn’t bothering her. She gave me a friendly nod.

But none of this was important because also in the room was the Goddess of the River Thames.

She sat enthroned on the finest of the executive armchairs. Her hair was braided and threaded with black cotton and tipped with gold, so that it stood above her brow like a crown. Her face was round and unlined, her skin as smooth and perfect as a child’s, her lips full and very dark. She had the same black cat-shaped eyes as Beverley. Her blouse and wrap skirt were made from the finest gold Austrian lace, the neckline picked out in silver and scarlet, wide enough to display one smooth plump shoulder and the generous upper slopes of her breasts.

One beautifully manicured hand rested on a side table, at the foot of which stood burlap sacks and little wooden crates. As I stepped closer I could smell salt water and coffee, diesel and bananas, chocolate and fish guts. I didn’t need Nightingale to tell me I was sensing something supernatural, a glamour so strong it was like being washed away by the tide. In her presence I found nothing strange in the fact that the Goddess of the River was Nigerian.

‘So you are the wizard’s boy,’ said Mama Thames. ‘I thought there was an agreement?’

I found my voice. ‘I believe it was more of an arrangement.’