Was luck enough to get a tour of the bird's egg collection at National History Museum at Tring, and also see some of the huge number of "skins" they also had. We were there to donate my father-in-law's egg collection - which they only accepted because it had his collecting notes from 30's and 40's (illegal now to even have such a collection I think). Anyway they did require passports to be presented when we arrived for tour, and said security was upped since someone had a tour and then came back and stole a significant amount of the skins.