In April 2021 a new temporary right was introduced under the General Permitted Development Order (GPDO) as part of the Government’s response to the Covid pandemic. (The GPDO specifies the types of development that don’t need planning permission). The new right allowed for the provision of ‘moveable structures’ within the curtilage of a pub, café, restaurant, or historic visitor attraction. The right was introduced to support greater use of outdoor spaces, for example to enable additional covered seating.
Subsequently this was made a permanent permitted development right, including in National Parks. Details are in this exploratory memorandum:
Paragraphs 7.8-7.12 explain the restrictions to this right including to the height, footprint and proximity to neighbouring residential properties of any structure.