He is delighted to discover that is the company building the iconic PV project across Blackfriars Bridge, spanning the River Thames below.

Working at the top of London’s towering Tate Modern art gallery, “people ask me about that project all the time”, the waiter informs Frans van den Heuvel. Then he pauses, lowers his voice. “So, what is it exactly, and how does it work?”

Two years ago, such an exchange would have been emblematic of Britain’s relationship with PV — with a public sceptical of the idea that solar energy had any place on their rain-lashed island, and a government asking questions not much more sophisticated than the waiter’s.