Sorry about the delay in reporting what we have done. Husband ended up replacing the Injector Harness himself and doing all the other little jobs that the Main Dealer had highlighted having taken note of all the helpful advice given by Forum members. He has also sprayed all the connections with a spray to remove any oil which may have crept down the wires of the main engine harness from the injector harness. So far the fault(Limp Home mode activated) has not re-occurred. So fingers crossed Many thanks for the help and advice. (If it doesn't work we will buy our own diagnostic reader as also suggested and take it further)

I'd be inclined to agree with iansoady, and will always agree with sierrafery.
I've noticed that in your original posting you said that the fault codes "have subsequently been cleared by the various people including a main dealer who reckoned that they were going to cure the problem".

Clearing the codes has no real value unless you know what the codes were so that measures can be taken to correct the cause at the same time.
That's why many Disco owners will tend to advise that you get your own code reader. Don't treat it as "computers", it's just another tool for the car, and relatively easy to learn to use. If you don't understand a code then just ask. Apart from anything else, it could save you a fortune if you don't have to visit the main stealer every time you need a fault code read.

Thanks Brian47 - As we intend keeping 'Big Red', our Disco(Yes, I do name all of our vehicles) we think that we will buy a code reader probably Hawkeye as it doesn't need a PC or laptop. This is because I use an AIO and my tablet isn't Windows. I have an old laptop but I'm not sure its up to the job as its seven years old and was really struggling last time I used it Hawkeye looked pretty straightforward and we have the actual Landrover Disco Official Workshop Manual which gives at least some of the codes and what they mean and I would ask members if got a code we didn't recognise Will let you know how we fair when we have actually bought the reader. Best Wishes Joy