Drove several of mine early this morning:
B1508 Colchester-Sudbury. Not many overtaking places but fantastic when deserted with three tight switchbacks (last one particularly is a double hairpin with plenty of visibility and scope for sliding the car about).
B1508 Sudbury to Castle Headingham. Short but very sweet with lots of straights ending in sharp bends.
Unnamed road from Sible Headingham to Wethersfield, joining the B1053 to Radwinter. Very fast, usually empty, some great dips in the road to charge down.
Anyone else got favourite routes in East Anglia?