Taking the train from Cambridge to Kings Lynn the Sustrans cycle path starts directly from Kings Lynn station. Following a lovely cycle only route for several miles through Kings Lynn and a number of villages the cycle path is generally well sign-posted throughout. As you cycle through the villages heading towards Sandringham the is a noisy part along side the main road which continues until you turn off towards the amusingly named Cat's Bottom.
At Sandringham the cycle route becomes busier with visitors to the queens estate filling up the roads but generally travelling slow enough not to bother you. You get to travel past the sawmill and off into the wilds of Norfolk. Essentially once you leave Sandringham the signs thin out and the only guide that you are on the correct route is the occasional  stuck on various sign posts. Heading up to Ringstead the path is quiet and passes through and around a number of nice villages and only once has a steep downhill ending in a junction.
At Ringstead there is a lovely cycle path to Burnham Market. However, just as you leave Ringstead the road bends right and what appears to be a quiet residential street is on the left. The cycle path actually continues down here, if you fail to turn off you end up in Great Bircham like we did. The sign to turn off is stuck to a lamppost hidden behind a tree partially embedded in a hedge we later discovered. We missed it traveling slowly on a sunny day so we can't imagine how hard it is to follow for a fast cyclist in fog. There is a great post office in Ringstead which sold us a good lunch. It also had a duck pond full of ducklings which entranced my girlfriend for some time.
The road to Great Bircham had a tar and chipping coating that eroded the energy, arriving there and finally figuring out where we were with the assistance of a local we headed off to the forest to meet the cycle path. This went without incident although the roads were a little busier and less cycle friendly. We did get a good view of the front gate to ?. Meeting the cycle path we were greeted with a few miles of gentle downhill which was nice.
Meeting the B road we then cycled the last part into Wells, and then onwards a mile to the Pinewoods campsite. The campsite was large, filled with noisy people, on one side we had two blokes on a 'fishing' holiday and on the other a couple of New Zealand girls who'd come to experience the UK's mind altering substances.
Heading back we followed the cycle path sucessfully into Great Bircham. Stopping at the Churchill for lunch which was very nice we continued along to Ringstead. This is much shorter and nicer than the previous route we took. It undulates gently but is otherwise superb. Travelling back into Kings Lynn from Sandringham you discover that most of the signs in Kings Lynn only make it clear how to get out on the cycle path, we regularly had to guess the cycle path route from memory and guessing which direction the sign should be viewed from.
Here is a convenient map with all the place names removed to make it extra difficult to use.