The lines are painted because it has been decided that the views are restricted and you are not fully able to make that decision.
Which by that reasoning means that even when the cyclist is travelling at 10mph or less you are not fully able to make a decision as to whether it is safe to overtake and therefore will be unable to overtake without risk even though it is legally acceptable.
Does this free reign to break the law be 'pragmatic' extend to passing tractors (round here they drive at about 15-20mph)? Maybe horses? or is this just reserved to 'must pass cyclist' incidents?
Read the HC to get your answer:
129
Double white lines where the line nearest you is solid. This means you MUST NOT cross or straddle it unless it is safe and you need to enter adjoining premises or a side road. You may cross the line if necessary, provided the road is clear, to pass a stationary vehicle, or overtake a pedal cycle, horse or road maintenance vehicle, if they are travelling at 10 mph (16 km/h) or less.
Laws RTA 1988 sect 36 & TSRGD regs 10 & 26
Whether you overtake the tractor is your decision based on whether you want to obey the law in a littoral sense or apply a degree of pragmatism requiring judgement.
Fortuitously, there is a degree of pragmatism exercised by Police as I have outlined with regards to lighting (HC 60) and that also extends to Audax as I believe we are expected to follow the appropriate law or risk the consequences.
I freely admit to breaking the law when I have been driving by going ahead of a Stop Line on more than one occasion. Glad the ambulance/police/fire behind me appreciated my pragmatic solution to enabling them to pass, even though I was breaking the law (in a littoral sense).
This debate appears to revolve around what is pragmatic and what is the littoral interpretation of the law. I only hope those espousing littoral interpretation of the law on this matter are not guilty of choosing when to apply a certain standard that is not maintained at all times, including cycling at night!