Planning permission is required if you want to short-let your entire London property for more than 90 nights in a calendar year. You would need to apply for a Change of Use from residential (Use Class C3) to short-term let use at your local borough council. For lets of 90 nights or fewer, no planning permission is needed. Planning rules apply to the property itself rather than the owner, so the 90-night limit applies regardless of who owns or manages the property.