Contradictions
To make a bad situation even worse, the government decided in all their wisdom to liven things up a little and break a few rules along the way.
Rule 1: Never block an entrance of a roundabout.
This leaves traffic free to flow where it can find an exit. If you need to stop and block an entrance then you're delaying drivers unnecessarily.
But oh no! On some traffic light controlled roundabout designs the idea is to deliberately block the entrance (s) in order to make traffic flow. The Handy Cross roundabout in High Wycombe is one such example. The traffic control system lets the roundabout "fill up" to capacity and then releases the vehicles before the entrance traffic proceeds onto the roundabout. A sound theory, except when exits are blocked due to traffic volumes the vehicles have nowhere to escape to, and all routes are blocked indefinitely.
Rule 2: Left hand lane for traffic going left, right hand lane for traffic going right, intermediate lanes for other exits.
Unless, of course, you're a road layout designer and want to have a bit of fun - at which point any lane you like can be used for any exit. Seriously, I can understand why sometimes you might use two lanes for one exit to help traffic flow, but I've seen some complete gems on roundabouts, forcing people who don't pay any attention to markings or signs to cause horrendous confusion and accidents. If the road layout bods are reading this: assume no-one reads words on the tarmac or lane guides on the signs. Some people are too damn lazy to pay any attention to which lane they should be in.
Spot the difference