@ColinJ I think you're right (970km, per mare per terram) even if you don't reciprocate. Please re-read my caveat ('roads' refers to start and finish not to 'using').
I don't think that is right! I just measured LEJOG as the crow flies, not using roads, and crossing vast swathes of sea
NB Limited by roads (which may not be public) as the start and finish.
LEJOG at 970.2km (sign to sign)
While on a roll and, having looked at your 'vast swathes of sea' condition (it's just over half over the sea),
the point to point distance for LEJOG over land, using cyclist crossable bridges across estuaries, firths. sea lochs and substantial rivers is 1109km (
http://ridewithgps.com/routes/11724790). These are:
Bridgwater (R Parrett)
Severn Bridge
Widnes-Runcorn bridge (across the Mersey)
Preston (R
Ribble)
Levens Bridge (SE corner of Lake District, over R Kent)
Carlisle (R Eden)
Longtown bridge (over R Esk)
Forth road bridge (Edinburgh)
Kessock bridge (Inverness, across the Moray Firth)
Cromarty Bridge
Dornoch Firth bridge (A9)
A9 bridge across Loch Fleet
So what? Well, I think it points up the chokes/turning points for route planning (whatever other criteria one applies (eg minimise English A roads, east or west coast).