For the record I don't mind being overtaken by motorists.
As long as it is done safely & is worth doing.
But with slow moving traffic it is often pointless.
When considering if I am holding up traffic it is worth remembering that the majority of delays to drivers are caused by other motor vehicles, road works, traffic calming measures (speed humps etc) and red lights.
The few seconds that I/other cyclists hold up drivers is almost always insignificant in comparison to delays by other causes (above).
The only times that motor vehicles would be significantly held up to justify cyclists moving over (if safe) to allow overtaking are on Xmas Day or on a race track.
I should point out that my average speed, on my £50 second hand bike and me not being very physically fit, during a London commute is 12 mph (this includes stopping at red lights etc) whilst the average speed of motor traffic is 11mph or less during rush hour.
Constructive criticism/feedback is welcome.
Trolls will be blocked.