Did an 'internship' at hedge fund, not sure if it's any good?

This summer I managed to beg my way into letting a london hedge fund give me the chance to 'voluntarily' (a.k.a. unpaid) spend some time in their HQ for 2 weeks.

They initially said they don't do internships and this sort of stuff, but I said that I would like the exposure to their sort of company and can shadow staff members.

So after they agreed, I turned up and I was basically assigned the role of an assistant to one of the portfolio managers. That involved getting coffee, newspapers, sorting out his mail, sending off any mail that he wanted and tidying up the paper mess in his office. I felt quite **** doing it, being a coffee boy dressed in a suit...but what the heck I get to put a hedge fund in my CV that's worth it.

It did involve some learning, I did get to be around some of the meetings between staff and he told me to feel free in reading his draft reports. He also quickly showed me how to summarise financial reports and input the time consuming data on their spreadsheets. I definitely learned quite a few things on the industry and have come out of it a little more knowledgeable than when I started.

However I am not sure now just how good these 2 weeks are, in terms of its significance on a CV when applying to IBs.

First problem is, it was unofficial 'volunteering', it wasn't like an internship that they'd have recorded on their HR database. So how will potential employers be varifying this? Should I ask them to provide a brief written and signed reference for evidence?

Second problem is is this something worth mentioning to potential employers? I don't want to sound silly mentioning this in case it's insignificant compared to a conventional internship (I've never done a proper internship for a corporation before...how different are they compared to what I did?).

Thanks.

Are you a first year at university?

so how will potential employers be varifying this?

is this something worth mentioning to potential employers?
Thanks.