A significant cyber security incident has affected Westminster City Council, the Royal Borough of Kensington and Chelsea (RBKC), and the London Borough of Hammersmith and Fulham. These councils share elements of their IT infrastructure, which means a single breach has caused a wide level of disruption. As a result, key public services, including planning and building control, are experiencing severe delays.
The attack occurred during the weekend of 24 to 26 November 2025 and led to an immediate shutdown of digital systems. The councils are working with the National Cyber Security Centre and the National Crime Agency to investigate the attack, secure their systems and restore services. Early reports confirm that some historic data was accessed and removed from council servers, which has added further complexity to the recovery process.
For anyone with a live planning application in Westminster or RBKC, or those preparing to submit new applications, the impact is considerable. The disruption affects:
In practice, this means that planning applications may take far longer than usual to progress through the system. Some services are currently unavailable, and others are operating with significant limitations. Westminster Council has confirmed publicly that full restoration will take time and that delays should be expected across all planning functions. The council confirmed to 4D Planning that as of 4th December, no applications have been processed in over a week.
Planning timelines in London are already stretched, and any interruption can affect project programmes, contractor appointments and financial commitments. For applicants working to tight deadlines, a delay in validation or a slip in determination dates may create real frustration. Developers, architects and property owners should factor additional time into their schedules until council systems stabilise.
This situation also shows how reliant the planning system has become on digital infrastructures and how vulnerable the process can be when those systems fail. With three major London boroughs affected at the same time, the impact is felt across a very large number of ongoing applications.
During periods of uncertainty, it becomes more important than ever to ensure that your application is well prepared, complete and ready for immediate processing once the council systems recover.
4D Planning can assist by:
We continue to monitor Westminster and RBKC (Royal Borough of Kensington and Chelsea) Planning Departments for service updates and will provide further guidance as more information becomes available. Watch this space.
If you are preparing to submit an application, you may wish to proceed with all preparatory work while accepting a delay in validation. If your application is already in the system, maintain realistic expectations and allow extra time for responses. If your project is time sensitive, contact us at 4D Planning so we can help you manage risk and adjust your programme accordingly.
The councils are issuing updates through their websites, though availability may vary during the recovery period. The latest statement from Westminster and RBKC Council can be found on their news page.
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