Thanks for the replies. I have also found this
So assume the Car Supermarket is responsible to find out what the fault is, so they need to be paying for the gearbox removal, stripping and inspection?
Having only done 2600 miles since I bought the car this gearbox problem I can only assume was already there when I bought it.
I am partially deaf, so the noise could have been there when I bought it, have only noticed it now as it is now loud enough for me to hear it!
I'll wait for a response from them and hopefully will not have any problems.