The details (with some excerpts) here.
This was described as a 'car crash' of an interview. Cameron became confused at times and disoriented and at one point forgetting it was a televised interview.
It's important to ask why his discomfiture.
Could have been he'd had no sleep that night, had had a row with his staff and was therefore out of sorts.
It is likely this was the case.
This does have some repercussions for our view of David Cameron. A PM, even if being evasive or just not very good, should still be more or less competent at doing interviews.
In my view it says something about Cameron, who he is and what his method is and spells big, big trouble for him and the country if he ever gets to be Prime Minister.
I think that he thinks that merely making a few glib sound bites is a sufficient stand in for policy making and maybe isn't even aware of the broader policy issues affecting LGBT people - hasn't even thought that there's more to this than learning a few cheap sound bites. Plus he has been given a kid glove treatment by the media and wasn't expecting a probing treatment by anyone - a bit of the old Etonian who is born to rule and needn't be scrutinised.