Planning objection in Westminster

We are regularly contacted to assist residents groups to object to planning applications.
One recent case involved us objecting to a proposed Certificate of Lawfulness for an extension in Westminster.
On paper the scheme looked permitted under Part 1 Class A.1 of the General Permitted Development Order (GPDO). The LPA took a similar stance and were going to issue the certificate.
Plainview Planning was employed to explore the detail of the GPDO and to establish a way to object to the CoL that was going to result in a 55% increase in floorspace. It was immediately apparent that the site was located within a conservation area, thus the relevant part of the GPDO was being incorrectly consulted by the LPA and the applicant.
Plainview Planning argued that the extension was tantamount a 2 storey extension that extended beyond the rear wall of the original dwelling (Part 1 Class A.2 (C)) and that the extension would extend beyond a wall forming a side extension of the original dwelling (Part 1 Class A.2 (B)).
Certificate of Lawfulness applications can go unnoticed due to the fact that the LPA are under no statutory right to consult neighbours.
*2014: we no longer undertake objections.