It is a requirement of NHS England that all patients must have a named accountable GP.
At Millcroft Medical Centre, this is the GP with whom the patient was registered when they first joined the practice.
Millcroft Medical Centre is a 10-partner practice, and this means that all the partners are accountable for the care of each patient, regardless of which doctor you choose to see. It may be that you are used to seeing one GP, but that your “named accountable GP” is a different doctor. This really makes no difference at all to your care, and you are free to see the doctor of your choice subject to availability.