the obvious wasn't obvious to me. so I looked it up on Hansard.
https://hansard.parliament.uk/commons/2019-11-05/debates/AABC4DE9-4D70-4937-9AF5-D58CE7B0601D/IntelligenceAndSecurityCommitteeReportOnRussia
//In accordance with the Justice and Security Act 2013, the impact of releasing sensitive information must be carefully considered by the Prime Minister on the advice of civil servants. We cannot rush the process and risk undermining our national security. There is no set timeline within the memorandum of understanding with the Committee for the Government to clear such reports for publication, and under the same memorandum there is no set timeline for a response, nor is such a deadline set in the governing legislation.
I want to assure the House that the Committee is well informed of this process, which is continuing along standard parameters that apply before every publication. Once the process has been completed, we will continue to keep all relevant parties and the House informed. //