A friend from the UK was wondering what this is (photographed near High Wycombe). Note - because of British history, there are many UK plants that are not native. John Farrer
A relative of a very rare species in BC, this is either Cephalanthera damasonium or Cephalanthera longifolia. A bit more of the plant would be helpful to ID, as it seems the length of the leaves is important for determining it. Perhaps someone more familiar with it will know, though.
I have added the three other pictures that came with that one - I don't know if they will be any help. John
I was originally leaning toward Cephalanthera damasonium, and the additional photos reinforce that suspicion to me.