SPI MCP23S08 to Arduino: strange stop/start behaviour
I have figured it out, lesson learned. I should have also drawn how my circuit connects to the Arduino, this would have probably then become obvious to me and everyone else. 

Basically I had MOSI -> MOSI and the same with MISO -> MISO, rather than crossing them MOSI -> MISO respectively.

Circuit working fine now duh!

Face-palm!