I have checked my series links list (there are over 200 programmes in the list but the vast majority are 'greyed out') and I did as you suggested for a couple of the 'culprits'. I then realised that all of the shows in the list were set to 'recordings and streaming videos'. This is obviously the default setting when I elect to record a series..
As these 'rougue items' appear on My Shows list, I will delete the streaming element and that should solve my problem (which is just one of annoyance).
So, as I understand it, every time that somewhere a broadcasting organisation is streaming an episode that is on my list, I will receive notification in 'My Shows' list, even if that stream is by a company for which I do not have an account (and therefore will not be able to access). In view of the potential, It seems odd that I only get about 8 of these notifications regularly coming through.
Again, many thanks for your advice