I think white bras are acceptable under white clothes, as it makes it plain that the odd bumps and back hamsters are because of said bra, rather than a deformity. But nude v useful for instances when bra show-through is not ideal. I think I have two nudes, one white, one black and one shocking pink. That fit. The rest are all sorts.
I'm feeling pathetically validated. On Tube Strike Day, when I had my PGCE interview, the local parents facebook page was awash with threads about the best way to travel in, etc. I was on nearly all of them, wailing and renting my vestments about being stuck on a bus, ruining the rest of my life, etc. So I thought I'd just tell them that it all worked out in the end. So far, I have more than 130 'likes'. Bizarre.