The goal of this protest is to make drivers of vehicles more aware of the moral superiority of cyclists, as cyclists generate less in the way of congestion than (larger) vehicles
In order to do this a percentage of those that would normally cycle will use a larger vehicle to get to work and back, hopefully leading to a massive spike in congestion
For the "normally motorised" to understand that they are being educated rather than simply delayed your major requirement is to get knowledge of LDtWD out there
Therefore this is a communications project, and penetration into the normally motorised of the day is going to be the best metric to judge success
Which would suggest that you need to promote this in places like Pistonheads, the Evening Standard etc, is this happening?
Relying on "the choir" to spread the word is not going to work
If it is only the converted who know whats going on, you have failed
Making some assumptions: