Ouch!
We don’t have building codes in this country unlike many. We therefore don’t have any prescriptive definitions of what might be an acceptable way to build. We do have Building Regulations but they are to do with the structural stability, insulation compliance, ability to use and escape etc.
We do have planning laws which have developed to control the sprawl of development and they set down criteria that was, and still is specifically not based on aesthetic design. They do ask for compliance relating to what you would call zoning, where something should be built, density and then criteria based on size of units and closeness to public transport for instance. And I paraphrase/generalise hugely here I know.
Design only ‘recently’ became a defined issue after a government of the day, you can guess which one, relaxed sizes of units and densities and people released that this freedom had produced questionable quality housing while acknowledging that the need for housing had not been met by the ‘free market’. This was set down in a document called ‘Urban Renaissance’. Since then successive governments have tinkered with planning legislation to try and maintain a market freedom while achieving , generally, housing numbers amongst other things. Fearing they were losing control over much of planning decision making, the local authorities who administer and make the planning decisions in the first instance, set down a further series of design criteria using their local legal powers.
Good design is very difficult to define successfully even if most people will understand that something may be well designed. That said, what you or I think is good design will certainly not be what other people do. This example is probably a case in point. Good design has also become the catch in every contentious planning application. If a local authority doesn’t like a scheme and wishes to reject it, even if most if not all planning criteria are met, will refuse it on design. Those planning decisions are then appealed to a central government department and the definition and quality of the design are argued over at great expense. And of course, planning decisions are made by the public called councillors who have to face re-election every number of years. They also have to go to the pub and face their neighbours when they have made a decision which might upset them. And that means that they may choose to refuse a perfectly reasonable and compliant design/scheme. Welcome to politics.
In this instance, it is fair to note that building at the bottom of a garden is out of proportion to the density of the neighbourhood and therefore there is an argument that allowing such development especially at this size, will unacceptably alter the character of that neighbourhood. The building is three stories in height and it would be fair to assume that three stories is also out of proportion to the character and scale of the neighbourhood. I may be wrong but the sort of suburban neighbourhood indicated on the plan would generally be two stories with a pitched roof. Again without knowing the area, inserting a three storey box looking building with upper storey terraces will almost certainly be out of context with the area too.
So we can safely say that the proposals are out of proportion etc. This doesn’t make it unacceptable hence the long discussion above about what to actually object on, privacy for instance which is strict set down criteria you can measure a design by.
And we are realising that suburbia does actually have its own very valuable character and sense of place. There is much other land in this country where development can take place. Increases in density can more reasonably argued next to stations, shops etc rather than at the foot of someones garden so that the land owner can make a significant profit. (but that has to do with land values and…lets not get me started about land values!!!)
Hope that helps.