On the way to work this morning, I stopped off at a shop, got back in the car, started the engine (mine is keyless), and within a couple of seconds, the engine cut out and the DIS displayed a message saying "Immobiliser Active", followed shortly afterwards by a yellow exclamation mark saying "Warning - Gearbox Fault". To say my heart sank is an under-estimation.
I turned the ignition off (via the stop start button), put the gearbox back into Park (from Drive where it was), re-started and everything perfect ! Carried onto work and no further issues. Checked the DIS under Vehicle Status and no messages, so fired up VCDS, and gave it a quick scan and no fault codes logged in any of the modules (Engine, Gearbox, Central Electronics - or in fact any of them).
I'm hoping this was just the KESSY having a bit of a brain fart, and deciding the key wasn't in the car for whatever reason, and the gearbox error was that I was in Drive with the immobiliser active not Park and the system threw a wobbler?