Thanks for the response guys.

I was trying to feign weaknes hoping that he would come over the top of me, so I flat called, he checked. Flop came 3 5 6, I checked, he pushed and I obviously called. Amusingly he had 2 4 and had flopped a straight.

With hindsight if I had wanted to act weakly I should have at least min raised, especially as I had been quite aggressive up to this point. At least he then would have had a decision to make; fold or push.