There are as few fond memories of childhood that I have as of Friday nights, when my father would demand complete silence so that we could watch Leo McKern work his magic.  Mortimer wrote the role especially for him, and when he passed, it was pretty clear that there would be no more episodes.  Happily for his fans, however, Mortimer continued to churn out works once a year or so.  Though the series had been dark for ages, I had always held out hope that, perhaps, someone like Michael Gambon would take over the role for just one more run.