Context and character- new detached house on a street of semis - Public forum - Planning Advisory Service (PAS)

I have just gone through a pre planning consultation for a proposal of replacing detached double garage with a new two storey dwelling in a London borough. The officer's main concern is the context and character as the proposed house is on a street of similar semis. He considered the fact that the house is detached make it out of character of the local area. 

I think I have seen quite a few similar development in the past in various borough. 

Anyone has any experience and view on this?