No way the biggest chalk pit in UK, certainly not area wise, I don't know about by volume of chalk removed. The big pit east of Bluewater at Dartford is considerably bigger than this quarry.I go past this most weeks and always tell myself need to go in one day... in fairness it's on one of my running routes and tricky to stop the running once started. Need to remind myself more forcibly to go in.. I will put a post-it note up on the fridge.
The online history is scarce. The only snippet of information that I have to add is that it is said to be the largest chalk pit in the UK.