Well I had my least productive day ever at the archives.
The further you get with your research, the more effort it takes. On Tuesday, it was like my ancestors were hiding. My visit was only redeemed by taking part in the "Getting to Know the Archives" talk, which was led by a nice chap called David Tyldesley who confirmed that I'd basically not been using the archives to their fullest extent but also took us on a tour of the strong room where I saw the original of the 1742 Guild Roll, which was great excitement for me.
As for my GGG-grandfather, I couldn't find him in the registers for Lund or Barton or Freckleton. I took my lunch in Kirkham hoping to see my GGGG-grandfather's gravestone at St. Michael's (couldn't find it) and then had a trudge around the former Zion church graveyard. If you have any ancestors called Whiteside, it's a great place to look! Couldn't find him there either.
I think this non-conformist thing seems to be a thread I need to pull at. I have it in my head that my GGG-grandmother (Margaret Raby) was non-conformist too, although I can't remember where I picked that up.
One of the things the chap at the archives said was that C of E churches are obliged to hand over their registers to archives, but non-conformists are not. I think I'll write to the present church and see if I can ascertain the whereabouts of their registers.