The short answer to the question has David Cameron the potential to be a great leader is yes.
I can now base this opinion at a close up peformance "Cameron Direct" in Llandudno last night. David actually answered some of the questions directly. Of course it was evident there were some prepared statements of policy based on other answers to expected questions. I have visited the Conservative web site and confirmed the policy statements there are consistent with last night's statements.
The impression I was left with was professionals in for example education, health and business would be trusted to use their judgement and be treated like experienced professional adults. I do hope David who can be expected to be the next PM of the UK based on the polls delivers.
It is easier to make policy and promises when in opposition.