The GMC allows Dr T to change gender. His registration states that he is male and "Not registered-having relinquished registration". I'm a retired doctor and my entry is the same status.
Dr E is female, with a different registration number and is now "Registered with a licence to practice". Dr's T and E have the same qualification date from same medical school, the same dates of provisional then full registration. So one can guess that they are the same person but there is no formal link between the two on the register.
My concern is that if a patient had had an issue with Dr T and looked him up on the register they might be reassured that he was no longer working as a doctor but that is untrue.
When patients have had a medical mishap they often say that they don’t want it to happen to anyone else. It's therefore quite wrong for them to be lied to by the GMC as to the status of the doctor that treated them.