Towing with permit aircraft
The Air Navigation Order at Article 87 restricts glider towing to those aircraft that hold a Certificate of Airworthiness. The CAA publishes a general authorisation that allows suitable aircraft with a UK National Permit to Fly to conduct glider towing subject to specified conditions including that it only applies to an aeroplane being used for the purpose of towing gliders whilst owned, or operated under arrangements entered into, by a club affiliated to the BGA.
You can view the recently published authorisation that replaces the previously published text here.