These are the individual files describing article processing charges paid by universities in the period 1 January 2017 - 1 April 2018. They were submitted by universities to Jisc in 2018.
This data has been cleaned, joined with previous years' data, deduplicated, and made available here: https://figshare.com/articles/APC_data_collected_by_Jisc_2013-2017/7264823