This is a very difficult situation, and once again I am going to move away from the particular and go to the general, not to evade the issue but simply because of the need for Chinese walls. A local planning authority cannot unilaterally withdraw a permission that has been granted. It does, however, have the power to revoke or modify a permission, if that is considered expedient. That action is subject to certain limitations, and requires the authority to pay compensation, which could in this, and in any other case, cause it problems.
If a third party feels that it has cause for complaint about how a local planning authority has handled an application, a concern in relation to the conduct of members of the local authority can be directed-as I am sure both Members know-to the Standards Board for England, the district auditor or the local government ombudsman.