“Oh yes, I’m helping to build a scale model of London, the way it was in 1840!”

What??Sane people were building a three-dimensional model of ALL of London, which in 1840 was the largest city in Europe, twice the size of Paris?

Can you imagine hearing a 21st century man you admire and respect, saying this in a perfectly serious and even casual tone of voice? The scale of the undertaking was so great that at the time it sounded daft to me, but my good friend David Armitage was dead serious.

Sec...