In one of the old buildings there were these narrow gauge wagons. We are not sure whether they are similar to those used at the Gunpowder Mill though...will check the next time we visit!
Royal Gunpowder Mills Waltham Abbey May 28th 2005
Photo from James & Martin's Picture Collection Copyright 'Jampics' m.hawkes7@ntlworld.com
British and Foreign Railway Pictures Jampics Fotopic.