Moodyman said:
Would somebody mind explaining what a 'Primary' is? with regards to junctions/lights?
I've seen it mentioned few times and want to understand what this means.
Thanks
Primary refers to a position in the middle of the lane, where you're effectively controlling the traffic behind. Usually used to increase your visibility and prevent people overtaking where ther is insufficient room. Needless to say, it doesn't always work, in that there's always someone who thinks his car is smaller and more important than it actually is.

At junctions, it means simply going to the head of the queue and positioning yourself in the middle of the lane, the reasoning being:
a) a cyclist is usually faster over the first 50m or so from a standstill than cars

it makes you visible to the cars behind, certainly more so than waiting next to the back of the passenger door
It's not always a good idea: I wouldn't do it unless I knew the queue wasn't going to move and I could see an escape route if it did. If you are filtering, you're usually more visible (hence safer) on the right of the traffic, rather than gutter hugging where you're reliant on drivers using that left hand door mirror - which few do - and vulnerable to people suddenly opening doors.
Possibly someone who's read "Cyclecraft" will be along in a bit to correct me on some points, but I think that's the gist of it, and it works for me.