Any planning application is open to public consultation, which gives any member of the public the opportunity to object to the proposals. The planning officers employed by the local authority will write a report setting out their professional view and making a recommendation whether or not the application should be approved. The decision on whether to grant consent or not then rests with elected members of the council.
The more objections, the more twitchy councillors get about granting consent. They want to get voted in again at the next local elections, and if they piss too many people off that isn't likely. Objections can make a difference. Sod the petition, lodge an objection to the planning application straight onto the Council website. Loss of an important leisure and sporting facility has solid planning grounds for objection.
National Planning Policy Framework paragraphs 28, 73 and 74 look to have some relevance here:
74. Existing open space, sports and recreational buildings and land, including
playing fields, should not be built on unless:
● an assessment has been undertaken which has clearly shown the open
space, buildings or land to be surplus to requirements; or
● the loss resulting from the proposed development would be replaced by
equivalent or better provision in terms of quantity and quality in a suitable
location; or
● the development is for alternative sports and recreational provision, the
needs for which clearly outweigh the loss.