NEXT had some that Harriet wore all of last year and I loved, I am not sure their new winter range has any in, but I picked a pair of the next size up in a NEXT seconds shop near us.
Actually you can have the 6-9 month pair if you liked? They are lined so quite warm and more baggy style than leggins - and to me they look brown, I don't really know what consistutes chocolate brown (and people wonder why I never got into fashion!)