The principal reason for refusal here is given as 'Having regard to the particular features of Nashleigh Hill, that the extent of the built form would be likely to diminish the spacious feel that presently characterises the immediate area.'
On the face of it there is space for a modest cottage on this corner plot (see location here), the site plan below indicates that there is some space around the existing dwelling, albeit there is a lot of vegetation to clear and retaining biodiversity is a key aspect of any planning application here. We can see why the planners might refuse, there is an open feel to this area and to approve a dwelling here might set a precedent for a series of applications which will transform the character of the area.
If you look at the location plan, the site area edged red is pretty similar to the size of the two plots to the south east on Sycamore Dene, and so in theory the site could accommodate two dwellings, but the planning refusal also comments on the large footprint of the proposal.
PAPA SAYS - The proposal needs to be reduced in size, to the absolute minimum, and a very careful assessment of the landscape and trees to try and establish the principal of a dwelling in thei location.