Those plans are misleading with regard the rear of the building.
For both first and second floor plans, it marks in the 'original' ground floor extent of the building, which includes the ground floor extension.

It appears that the new building will project out to a similar extent as now, but this is not the case.

For the whole of the second floor, the current building aligns with the other houses and that is true for the first floor also, apart from a narrow half-height attic room extension.

If this building is allowed to project to the rear, why not their neighbours more-so, in a race to the back fence?