A quick rundown
A single yellow line must be (normally) 100mm wide and terminated at both ends with a "T" bar that extends 100mm out on both sides of the bar.

A double yellow is similar, i.e. lines are 100mm wide with 100mm gap between them. the termination is slightly different. in that only 1 100mm bar extends of the end towards the pavement

The important thing to note is that the road traffic act states clearly and repeatedly the "no variation is permitted" to its specified measurements.

Get a tape measure or ruler. make sure the line is terminated. If it is, make sure it is evenly terminated i.e. 100mm both sides (I have had tickes cancelled because it was 90mm one side and 110mm on the other.

Also, where a single yellow line is not part of a controlled parking zone, there must be a sign giving details of time restrictions on every LAMPPOST for the length of the line.

Less than 30% of the lines in my town are valid. If you take a photo of the lines termination at both ends and send it to me I can advise you better.
( RadG Drinking Mojitos in the sun, Thu 21 Aug 2008, 10:58, Reply)