He was such a nice young man. He was pleased I was going to buy the book, partly because it soon became obvious that no one had ever wanted even to look at anything in the case, much less buy anything out of it, and partly because if I bought something I might then leave.

The only snag was the key.

He looked in all the drawers of all the desks. He looked in the filing cabinets and the cupboards. He looked on various hooks and shelves. Finally he turned to me, apologetically. No key. End of the road.

I knew he could try harder and, if it weren’t for the builders and the phones, he would. I mentioned that I was keen to buy it because my ancestor, a convict sent to Australia, had been a lighterman…Now I had his attention. All the way from Australia! In that case, we must find the key.

He looked again, more thoroughly, in all the drawers. He opened the safe and fossicked in there. He rang up someone else to ask. It appeared that the only human being on the planet who knew where to find the key of the locked glass case in the front office of the Watermen’s Hall was Old Harold. Old Harold was on an errand somewhere, and would be back at some unspecified time.

I nearly didn’t wait. The book was looking less fascinating every moment. I wasn’t interested in a tie or a mug. But something kept me standing there, trying to stay out of the way of the builders as they massed in the tiny room wanting to know what to do about the junction box.

The minute Old Harold arrived, I knew it was worth the wait. Old Harold was a man not very much older than myself. He was a smiling balding person of great calmness of presence. I got the feeling that Harold had been waiting all his life for someone to come along who found the watermen as interesting as he did. That person had now appeared, in the shape of a dishevelled woman from Australia.

Old Harold found the key, I bought the book and waited till the young man was busy on his mobile. Then I quietly asked Harold whether I could have a look around. Harold— with a quick glance at the young man—jerked his head sideways. I followed him through the room with the glass cases, out into the stone-flagged passage, and up the lovely staircase.

At the top of the stairs he stood back to usher me into a big peaceful room. A radiant window filled one wall, the watermen’s crest glowing on it. Under it, three enormous wooden tables were arranged like a judge’s bench. Whiskery gentlemen frowned out of gravy in gilt frames on the walls.

Harold told me that this was the room where, as a would-be apprentice to the Company of Watermen and Lightermen, he’d been ‘bound over’ some forty years earlier. The masters, daunting men in black suits, sat up behind the table quizzing the boys about the river rules.