The ghost in the machine.
In a way the Prisoner-No.6 is in the series, but in the guise of the old man 93. However, and I suspect this might have been too expensive to do for very long. But do British readers recall a television commercial which featured a number of actors on a modern day train journey, actors like Cary Grant, the Railway Children, John Mills appeared in the commercial, as you will see by clicking on the link below.
I know that Patrick McGoohan as the Prisoner-No.6 appeared in one of these adverts, but I cannot find it on YouTube. But you see what I mean by watching the advert, by this technique one could resurrect Patrick McGoohan in his role as the Prisoner!