...But I was caught out when I started to follow NCR 1 from Berwick and it degenerated in to a footpath that is just not suitable for a heavily loaded road bike and follows a very dangerous (in my opinion) cliff top route. This is not the first time I have come across problems with NCR 1. ...
It was no better on a heavily laden expedition bike with off road tyres either, but be thankful - it could have been a couple of the sections we had in Scotland (of other NCR's). We had sections through a nature reserve where we had to remove all the panniers (and therefore our rackpacks as well) to get through the barriers and after the 2nd time in the space of 1/2 mile we returned to the road. Another section through Scotland (NCR77 I think, around Dunkeld station) the cycle route has steps on it, and not just one or two - if you know you can follow the road, and then almost immediately afterwards it has you cycling up a slip road AGAINST the flow of traffic that is coming off the A9... There was a narrow pavement but with no dropped curb to use and road markings saying use the sliproad, it was clearly an after thought by the insane... Then around Prestonpans I think it was, very steep steps to go around a power station, again the road or even the pavement you were previously cycling along would have been a better option...
Then you could consider the insane patch of NCR1 where it leaves the A1 and goes down to Lindisfaerne... Between the petrol station at the A1 junction and "The Barn at Beal" where we camped, the cycle path crosses the main road something like 5 times in the space of half a mile - we followed the road instead on the return journey only to be verbally assaulted by a motorist for not being on the cycle path - the only time in 14,000km/8,700miles that we had that problem!
The cycle network in the UK needs more thought and planning, we accept in because we have nothing else except dangerous roads with overly agressive drivers, no other reason. Cycling aroad in much more enjoyable IMO.