How can I look unsafe to a car driver but be safe This research seems to show car drivers give you more space if they think you are more likely to do something unpredictable. 

It claims that where a cycle helmet often results in drivers giving you less space.

So how I make a driver think I am not a safe cyclist without being unsafe.

Is this the reason why the cyclists I always saw in Cambridge without lights never seem to get knocked of their bikes, but “safe” cyclists I knew with good lights and reflective jackets etc did sometimes (not often) get knocked of their bikes? 



Direct link to research and a blog post by the researcher.
Try not hugging the edge of the road, drivers will be more tempted to squeeze past through smaller gaps if you're right at the edge. Instead ride about 1/4 of the way across the lane, it might p*** off a few drivers, but it will make them think twice about squeezing past with overtaking traffic / parked cars / etc.