No specific, verifiable evidence detailing London Underground's institution and maintenance of cleaning and maintenance standards has been provided in the input. While searches on gov.uk for "Fennell Inquiry recommendation implementation" indicate the existence of related official documentation, the specific content describing implementation for FENN-72 is not available. No relevant legislation has been identified on legislation.gov.uk. Given the inquiry's age (1987), and the absence of specific published evidence of action, the status is unclear.