Bit of an update on this.
I was a bit hasty in dismissing the tv_grab_zz_sdjson grabber - it seems that I did not give the grabber enough time to fully populate the guide.
My guide is now populated with full episode and season information for the large majority of programs - it is not 100% perfect but it is very good.
Unfortunately, series link does appear to have been lost - if I go into the TVH WebGUI and click on a program now, instead of getting the "Record Series" button, I get "Autorec".
I am in a bit of a dilemma now, do I prefer a fuller EPG or the series link facility? I assume that I cannot have both.
In reality, is Autorec perhaps 99% as useful as series link anyway?
For example, as long as the title of the show does not change, Autorec should record all shows with that title but with an episode not already recorded.
The only time I can think I had a problem was when my other half was recording Big Brother. On certain days, you would have the main show "Big Brother", but then later that day you would have "Big Brother: Live Eviction" - I am imagining that the Autorec function would not pick this up but series link would.