The Prof is Guyanese, and as I left I asked him why their batsmen mark the crease by banging a bail into the ground.
'The land is Amazonian clay,' he said. 'There's very little sand. In the dry season, it's as hard as concrete. Most of them don't have spikes. They wear soft shoes. Banging the bail in is the only way you can make a mark in Amazonian clay'.
NB: He also gave me a copy of his latest book, which I look forward to.