Sadly, there are many series with missing episodes for whatever reason (i.e. the Hercule Poirot series) and other Australian shows which were recorded on the old VCRs by TV channels and then broken, lost or recorded over.Hah, 30 years old?
I'm trying to re-watch Dr Who. Unfortunately many missing episodes from the Hartnell and Troughton years but I'm almost up to Pertwee so I'll get colour and no missing episodes soon.
I'm up to the end of Troughton so 55 years old.
Might take a couple of years to get through them all!
DS