A relevant consent may be given—
unconditionally or subject to conditions, and
generally or specifically.
The Mayor may vary or revoke a relevant consent except in the case of anything already done, or agreed to be done, on the authority of it.
A variation or revocation under subsection (2) does not have effect until the Mayor has served notice of it on the person to whom the relevant consent was given.
In this section "relevant consent" means a consent of the Mayor required under this Chapter.