The first measure that comes to mind is the fact that each and every employee at the office, without exception, has secret security clearance. Second, we use the networks provided to us by the House of Commons, and we're assured that they are extremely secure and encrypted. Third, we have a registry that is locked, basically, and requires a magnetic card. We also have 24-7 coverage by the House security service to make sure there is no intrusion into the office. Fourth, we also have a clear policy that employees should only consult a file on a need-to-know basis.
On December 14th, 2021. See this statement in context.