Interestingly just read this from Post elsewhere... kinda answers my own question....
NS Level 2.14. Deciding where cycle lanes can help a journey & demonstrate correct use
The cyclist should always take the position that will be safest for them. In judging this we should consider what manoeuvre they are undertaking and, in light of the guidance on individual outcomes, decide whether a cycle lane they could use would enhance or detract from their safety in each instance. Cyclists should be aware that it is their choice whether or not they use cycle lanes or facilities and that often it may be safer not to.
The quality of design of cycle lanes and facilities varies greatly. For example, where lanes are wide, (1.5 metres or more) these should be adequate for use when riding ahead. Where lanes are narrow, unless the cyclist can use them to filter past queuing traffic (taking appropriate care as they do so), they will undoubtedly be safer riding in the primary position outside the cycle lane. Cyclists should also avoid cycling in lanes where the surface is poor. Cycle lanes can often be blocked by parked vehicles and other obstructions or be so short and/or narrow that their use would be unreasonable and getting in and out of them expose the cyclist to more risk.
National Standard for Cycle Training, Guidelines for assessors September 2006
The National Standard recognises that cycle lanes are often not the safest places for cyclists to ride; many lanes are narrow and position riders where they are less visible. Riders may feel safer riding in a cycle lane whereas they may actually be riding in a more risky position.
Recent research supported by CTC has shown that drivers give less room to riders riding in cycle lanes than riders riding on roads with no cycle lane.
Interestingly just read this from Post elsewhere... kinda answers my own question....
NS Level 2.14. Deciding where cycle lanes can help a journey & demonstrate correct use
The cyclist should always take the position that will be safest for them. In judging this we should consider what manoeuvre they are undertaking and, in light of the guidance on individual outcomes, decide whether a cycle lane they could use would enhance or detract from their safety in each instance. Cyclists should be aware that it is their choice whether or not they use cycle lanes or facilities and that often it may be safer not to.
The quality of design of cycle lanes and facilities varies greatly. For example, where lanes are wide, (1.5 metres or more) these should be adequate for use when riding ahead. Where lanes are narrow, unless the cyclist can use them to filter past queuing traffic (taking appropriate care as they do so), they will undoubtedly be safer riding in the primary position outside the cycle lane. Cyclists should also avoid cycling in lanes where the surface is poor. Cycle lanes can often be blocked by parked vehicles and other obstructions or be so short and/or narrow that their use would be unreasonable and getting in and out of them expose the cyclist to more risk.
National Standard for Cycle Training, Guidelines for assessors September 2006
The National Standard recognises that cycle lanes are often not the safest places for cyclists to ride; many lanes are narrow and position riders where they are less visible. Riders may feel safer riding in a cycle lane whereas they may actually be riding in a more risky position.
Recent research supported by CTC has shown that drivers give less room to riders riding in cycle lanes than riders riding on roads with no cycle lane.
From here: http://www.cycletraining.co.uk/news/Briefing%20Paper%20Met%20police%20driver%20training.pdf