Paul,
I'm leaving Tring (the other side of Herts) at about 6.15-ish, and will be passing north of Stevenage at around 7.00ish, do you think you're leaving a bit early??? Should only be about 65 miles on straight-ish unpopulated (at that time) roads from Baldock to Snetterton - obviously I'm planning to stay well within the speed limits...
If you think you'll still be around at 7.00, let me know
Jas
P.s. Just looked and there are 5 speed cameras on the A505 and 3 on the A11 - as Shaw Taylor used to say on Police 5............'Keep 'em peeled'