This one is a bit frothing at the teeth, but I do recall a few others from after the congestion charge was introduced. It ended up being a minor controversy, and I could have sworn I read confirmation from later on, after the Ken Livingstone was no longer Mayor.

https://www.independent.co.uk/news/uk/home-news/revealed-how...

And then from not long after it was introduced, you can see the AA blathering about it again: http://news.bbc.co.uk/2/hi/uk_news/2967852.stm

side note because I'm getting down votes: I'm one of those strongly in favour of congestion charges. I believe they made an improvement in London and not just because of these stunts. Of particular value was shifting a bunch of large vehicles to off-peak.

Anyone who has ever tried to adjust the phase of a traffic signal can tell you that sneaking little changes, all over a large city, is fantasy.