Grey is the colour you go for when you feel in a good enough mood to not wear black, but the mood isn't quite good enough to tempt you into a more statement defining colour. I have far too many variants of black blazers it's almost irritating: I don't know how I accumulated so many black blazers (in different styles!) and yet not a single one is grey. I have a grey coat, like the first two images above, but a lot more formal -dressing down with it looks great because of the contrast but it's also hard to dress down because of it's strong structure. I'd love to own one of the above two coats, I would use and abuse it to no end.
My uni is taking us all on a trip into the heart of London (more specifically to The Gherkin for a lecture) and I'm kind of unsure as to what to wear: how formal do I go (I'm only a student)? My classmates who are guys will wear suits, so should I wear a suit? I don't feel completely comfortable in a suit, but I don't want to stand out in a dress (particularly as it will require wearing heels and I don't want to over tower the guys, which I will end up doing!). I honestly don't know how women working in the City do it!