“Really? You never heard that story?” Billy carried on, “Well, Prime Minister John Major was hosting a function for President Clinton at the House of Commons. There was a question of security. Dillon said it was crap and that he could make it onto the terrace dressed as a waiter.”

“He what?” Roper was incredulous.

“But it could only be done from the river, see? He conned Bernstein into finding him the biggest expert on the River Thames, only it wasn’t anyone in Customs or the River Police.”

“It was me,” Harry said. He smiled. “God bless her, she never forgave Dillon.”

“And why would that be?”

“We’d a little bit of business. Diamonds on a boat from Amsterdam coming upriver. There was an informer at work. Bernstein knew we were going to be nicked that night here on the wharf. We’d have gone down the steps for ten years each, only Dillon here decided to be a naughty boy again, which meant the police didn’t catch us with the loot.”

Roper turned to Dillon. “You dog.”

Dillon reached for the third Bushmills Dora had poured. “It’s been said before.”

“The Superintendent wasn’t pleased at all. Since she works for Ferguson, she’s covered by the Official Secrets Act, which meant she couldn’t open her mouth.” Salter shook his head. “So, as I said, I don’t think she ever forgave Dillon for that, especially as, with our assistance, he did indeed make it to the terrace at the House of Commons dressed as a waiter, and served canapés to President Clinton, the Prime Minister, Ferguson…”

“And let me guess,” Roper said, “Superintendent Hannah Bernstein.”

“To be accurate, Chief Inspector, as she was then,” Billy said.

His uncle nodded. “And still a lovely girl.” He shook his head. “However, if we were capable of getting Dillon onto the terrace at the House of Commons to serve canapés to the President of the United States, we ought to be able to come up with an answer to this present puzzle.”