Talk of Cadbury reminded me of the many hours spent at Bourneville when Tilcon’s West Midlands based surfacing gangs (ex Val de Travers lads mainly) were resurfacing most of it. Coach loads of women used to arrive to buy stuff in the ‘cut price’ factory shop, however (according to the workers there) it was cheaper in supermarkets! 
Cadbury also had a works at Knighton that we sometimes delivered chatter or scalpings to when they had buildiing work going on, it was on the canal network and even at that late stage (1980’s) still sent barges down to Bourneville.
Still there but now owned by Knghton Foods it seems;
Pete.