Ok thanks Staggerindragon for the info, great. I also like the Hadrian's wall and C2C linkup idea. It would be a nicely varied trip to keep things interesting.
If I consider a clockwise loop in stages, doing Hadrians wall West to East, and the C2C East to West, there are only three short pieces (2, 4 & 6) I can't figure out. Anyone have any ideas?
1. Whitehaven to Allonby (on England Coast Path, 22mi)
2. Allonby to Bowness-on-Solway? Looks like the ECP for Allonby to Gretna does not exist yet?
3. Bowness-on-Solway to Wallsend (on Hadrians Wall Path, 84mi)
4. Wallsend to Seaburn? 11-ish miles
5. Seaburn to North Gare Beach (on England Coast path, 34mi)
6. North Gare Beach to Saltburn-by-the-sea? Is there an ECP section open for this?
7. Saltburn-by-the-sea to Robins Hood Bay (on the Cleveland Way, 27mi)
8. Robins Hood Bay to St Bees Head (on C2C, 184mi)