Are the pads "metalized?" If so, you might try buying a different type of non-metal pad. Also, I don't know about the MG, but many cars with disk braks have "squeel reducers" (little metal springy strips that sit behind the pads). If you car has them, make sure they are in place and in good shape. If all that fails, have your rotors checked/turned as necessary. If you have "hot spots" in your rotors, that can cause problems as well. Good luck and let us know how it goes.
By the way, I'm moving this message to the "MG forum" as "Car Care" is really more for discussions of cleaning, detailing, polishing, etc. Ho, and welcome to the forum!
Basil
Post moved to "MG Forum"