Seddon House (completed in May 1974) is a north to south terrace block, sitting between Thomas More House and Lauderdale Tower. It is on the western side of the estate, overlooking Thomas More Garden. The block is similar in form to Gilbert and Mountjoy Houses, but has slightly fewer flats on each floor.
There are 5 storeys of flats above podium level with penthouse maisonettes above that. Seddon House has 75 flats and maisonettes, ranging from one-room studio flats to five-room penthouse maisonettes. The flats are numbered 101 - 112, 201 - 212, 301 - 312, 401 - 412, 501 - 512, 601 - 612, 701 - 703.
An access corridor runs through the middle of the block, with lifts and staircases at each end. There is a very spacious lift and stair foyer at the north end, with attractive exposed concrete. They skimped at the other end where the lift lobby is just painted white. The flats are arranged on either side of the corridor. Unlike some of the buildings, Seddon corridors have decent central lights. Woodwork is generally painted a a dignified turquoise colour.
At 03 level, arches open on to Thomas More Garden at the south end. Car owners cross a cobbled road in front of the Thomas More garden flats to reach Thomas More House car park, whose entrance is off Aldersgate Street, just under London Museum.