On all the advice forums connected with the MG ZT and Rover 75 it is recommended that you must fit the orange clip (or white clip as they are now coloured). This is a clip to add to the fuel filter housing that is located in the fuel tank to stop it coming apart – and consequently causing the car not to start.
So I bought a clip and waited for a dry spell to do the job. It means removing the rear seat, removing a panel on the floor to expose the fuel tank and then taking the fuel filter out to fit the clip.

So removed the rear seat base and found some rubbish that had accumulated over the years. Fortunately i checked what the papers were to find one was a receipt and the other the empty bag that once held an orange clip. Was obviously fitted by SMC who were selling all the Rover stock of cars on behalf of the receivers.
That was enough evidence for me to decide the clip was already fitted and so would not have to mess about with the fuel tank. So job done ……. wish I had found out before battling with the rear seat squab to get it out!