City riding lights - flash or steady?

Seen alot of blue LED lights front and back lately around where i live. Not too sure what sort of trend it is but it seems to be catching on.

Probably due a PCSO crackdown.
A blue, rear light would get you cracked-down on, no?

Blue front lights aren't legal either, are they?

...I also sometimes use two steady lights on the front and if they are suitably bright oncoming traffic thinks you are a motorbike, especially usefully on poorly lit rural or urban streets.
I've noticed this too. I have twin, front and rear lights (mounted side-by-side) and find that traffic treats me much more cautiously in unlit areas.

Oncoming traffic dip their lights sooner and overtaking vehicles slow down before overtaking, rather than keeping their speed up and swerving around me.