Resolved- 3¾ hours there, 4½ hours back including getting lost in my own back yard by way of the unsignposted diversions on the A120. Total trip stats of 367 non-motorway miles at an averaging of 43 mph. I now have an alternative 'avoid motorways' route to 'North of Watford' to my usual A134/A47 route. Thank you John & Sonia for a fantastic day, well worth the ride over and rock cakes just like my 92 year old Mum makes, must be a generation thing.