What is this cut off cable from mid section of the exhaust system is it important? I am still waiting for a workshop manual to arrive.

Cat temp sensors.

 

All the sensor does it light up a symbol on the dash to warn you that the cats are overheating - which is typically due to a missfire issue with unburnt fuel entering the exhaust system.

Thanks for the info, do I need to re connect it?

No need to. Has no affect on the running of the car. They are often cut, typically becuase a mechanic/garage had to remove exhaust but could not undo bolt. They are also removed when people fit decat pipes.

Thanks that has put my mind at rest, I only need to worry about the slightly smokey turbos?!