Ok, piece of piss.
Socket
Socket extension bar
10mm socket
Undo the top and bottom bolts being carful not to drop them into the engine tray. Let half the coolant run down the street, turn the thermostat 90 degrees anti-clockwise and it pops out.
Housing is attached to a rad hose but I didn't bother undoing it.
Stuck the thermostat in a jug of boiling water and it done sweet f.a so this might be the reason the car isn't heating up over 50 degrees for the first 10 minutes of driving.
Refitting is the reversal of removal.
Don't forget to top it back up.