I worked it out.
If you look at the masking on the board it has a legend -=Camera, ~=SD and * = psram. Pins 38,39 & 40 had a tilde (~) next to them.
So, by using a spy glass and continuity testing I determined that the CMD, CLK and D0 pins were connected to 38,39 & 40, respectively.

I couldn't find ...

I am getting to grips with the IDF. Thought I would try the SD card reader on my ESP32s3 WROOM 1 N16R8 OTG UART board.

Apart from setting the flash memory size, I've altered nothing but it fails with

I (861) example: Initializing SD card
I (861) example: Using SDMMC peripheral
I (861) example ...