section 12B (right of qualifying tenants to compel sale, &c by purchaser), or
section 12C (right of qualifying tenants to compel grant of new tenancy by superior landlord),
If at any such time the nominated person becomes aware that the number of qualifying tenants of the constituent flats desiring to proceed with the disposal is less than the requisite majority of those tenants, he shall forthwith serve a notice of withdrawal.
If a notice of withdrawal is served under this section the purchaser may recover from the nominated person any costs reasonably incurred by him in connection with the disposal down to the time when the notice is served on him.
If a notice of withdrawal is served at a time when proceedings arising under or by virtue of this Part are pending before the court or the Upper Tribunal, the liability of the nominated person for any costs incurred by the purchaser as mentioned in subsection (3) shall be such as may be determined by the court or (as the case may be) by the Tribunal.
The costs that may be recovered by the purchaser under this section do not include any costs incurred by him in connection with an application to the appropriate tribunal.