WebScreen is a highly flexible web filtering system designed and built for the UK education sector, fulfilling the requirement of the Department for Education’s statutory safeguarding guidance ‘Keeping Children Safe in Education’ to offer 'appropriate filtering'. Its user manual is online at https://webscreen.lgfl.org.uk/UserManual/index.html
This system is capable of decrypting your 'https' traffic for monitoring and filtering purposes.
Using the certificate only in Firefox, not system-wide, is recommended.