can anybody please settle an argument

[wilderness]

on a british road what is the meaning of a double unbroken white line down down the centre of the road

[sqad617]

No overtaking?

[Quizmonkey]

No crossing of that line except in an emergency.

[Norberto]

Further to above.
No overtaking in either direction.
Sometimes you see a solid line and a dotted one. In this cse you can overtake if the dotted line is on your side of the road.

[sddsddean]

It DOES NOT mean no overtaking (though many people think this, basically as that is what they are taught by their instructors). As QM says, you may not cross the line, except in an emergency or for the purposes of turning right. So you could overtake a pushbike (as long as you don't cross the white line), or turn right into a driveway. Normal junctions would not have a solid white line across them. Also, Norberto say, the solid white line applies to the side of the road you are on, so a double white line just means neither direction are allowed to cross the white line. Whilst this effectively means no overtaking, that is not the meaning of the white line.

[Brooksy]

Where the solid line is nearest you, you must not cross or straddle it unless it is safe & you are entering premises or a side road. You may cross the line to pass a stationary vehicle or obstruction, or overtake a pedal cycle, horse or road maintenance vehicle doing 10mph or less. Going up long steep inclines one often finds two lanes on the left, twin solid lines, & one lane coming down, so "no overtaking" has always been the wrong populist answer.

[Ethel]

It also means you MUST NOT STOP except to drop off or pick up passengers.

One that gets forgotten sometimes is that it is an offence to park where there are double white lines in the centre of the road � even if there is room.
http://www.iam.org.uk/pressroom/drivingtips/Dr iving+tip+21+June+2007.htm