The ONS has published Local authority green belt statistics for England: 2016 to 2017.
The extent of the designated Green Belt in England as at 31 March 2017 was estimated at 1,634,700 hectares, around 13% of the land area of England.
Overall there was a decrease of 790 hectares (less than 0.05%) in the area of Green Belt between 31 March 2016 and 31 March 2017. In 2016/17, eight local planning authorities adopted new plans which resulted in a decrease in the overall area of Green Belt compared to 31 March 2016.