I think the reason lies mainly with the fact that no-on ever knows anything about classical music apart from my best friend, and no-one ever really cares- so I haven't had a large amount of practice in talking about it.
When someone DOES ask me about something to do with classical music, I know they don't really care and don't understand any of the basic concepts, so I give them a quick jumbled up explanation because I don't feel I've got the 'platform' to talk about it properly.
I can talk about things fine when I'm teaching, because I have absolute authority, but then I'm not teaching as advanced stuff as I'm studying. I think the problem lies in trying to convert my knowledge into something I think one of my friends will both be able to understand AND care about.
Obviously I've talked to my tutors, but that experience I find difficult because the majority of the time they'll interrupt and put me off my track, and specifically my personal tutor has a way of phrasing questions so they cut right to the bone of the issue, which is hard to come up with an off-the-cuff response to.
Another issue is that I never give an opinion for anything I'm not 100% sure about and I dither on the fence all the time. It's not that I don't understand the issues, it's just I hate tailoring information into a cohesive whole when it can't be pushed that way and I'll NEVER argue something I don't personally agree with.
I think that is the main reason why I'm not Oxbridge material- I can't bullshit an essay out by creating arguments from premises I don't agree with. Having said that, I've never ever tried, but I can't imagine doing it.