General Discussion

I thought this info might be useful.

The following are the grounds on which planning permission is most likely to be refused (although this list is not intended to be definitive) : 

• Adverse effect on the residential amenity of neighbours, by reason of (among other factors) noise*, disturbance*, overlooking, loss of privacy, overshadowing, etc. [*but note that this does not include noise or disturbance arising from the actual execution of the works, which will not be taken into account, except possibly in relation to conditions that may be imposed on the planning permission,dealing with hours and methods of working, etc. during the development] 
• Unacceptably high density / over-development of the site, especially if it involves loss of garden land or the open aspect of the neighbourhood (so-called ‘garden grabbing’) 
• Visual impact of the development
• Effect of the development on the character of the neighbourhood
• Design (including bulk and massing, detailing and materials, if these form part of the application) 
• The proposed development is over-bearing, out-of-scale or out of character in terms of its appearance compared with existing development in the vicinity
• The loss of existing views from neighbouring properties would adversely affect the residential amenity of neighbouring owners
• [If in a Conservation Area, adverse effect of the development on the character and appearance of the Conservation Area] 
• [If near a Listed Building, adverse effect of the development on the setting of the Listed Building.] 
• The development would adversely affect highway safety or the convenience of road users [but only if there is technical evidence to back up such a claim]. 

The following points, on the other hand will not be taken into account in deciding on the acceptability of the development in planning terms : 

• The precise identity of the applicant; 
• The racial or ethnic origin of the applicant, their sexual orientation, religious beliefs, political views or affiliations or any other personal attributes; 
• The reasons or motives of the applicant in applying for planning permission (for example if the development is thought to be purely speculative); 
• Any profit likely to be made by the applicant; 
• The behaviour of the applicant; 
• Nuisance or annoyance previously caused by the applicant [unless this relates to an existing development for which retrospective permission is being sought]; 
• Concerns about possible future development of the site (as distinct from the actual development which is currently being proposed); 
• Any effect on the value of neighbouring properties
 

From: http://planninglawblog.blogspot.co.uk/p/how-to-object.html