DuCane Court in Balham has a number of different styles of flats and apartments from tiny studios to large 4 bedroom duplexes and flats with private balconies.
Here are two floor plans for Du Cane court 1 bedroom flats one with the living room on the left and one with the lounge on the right. As you can see not all the one bedroom flats in Du Cane are the same size. They can vary quite considerably which means that the prices you pay to rent or purchase will also vary.
One of these flats is 524 sqft approx 50 sqm and as you can see follows the usual pattern of the bathroom and kitchen taking up about the same amount of space as a room. This is much more noticeable in the 2 bedroom apartment floorplans which have a larger hallway. The other is about 25 sqft larger.
You can view many more floor plans using a simple image search.