additional 31 to a modified 'I' shaped design to make use of small sites. These are all known as Mark I blocks. A modified design introduced in 1961 altered the external appearance of the design very considerably, whilst not appreciably affecting the layout or number of the internal rooms. The ends of the arms of the 'H' blocks were connected by a hollow block concrete screen, and additional and larger rooms were provided, each with its individual balcony. Ninety-four of these Mark II blocks were built between 1961 and 1964; Appendix 11 shows a typical layout plan.
58. Each wing of the Marks I and II blocks is divided structurally into a series of bays, 10 feet wide and about 25 feet deep. Originally these bays were sub-divided by partitions down the centre line, producing rooms of approximately 120 square feet (12 feet 6 inches × 9 feet 6 inches) which is still the standard size of room in the Marks I and II estates. Ventilation is afforded by a door and by a large window which opens on to the communal balcony, and also by openings in the common partitions at the back of each room. Government decided in 1954 that these rooms should accommodate five adults (two children under 10 counting as one adult), at a density of 24 square feet for each adult. It was not an easy decision to accept such a high density, but bearing in mind the very large number of people who had to be resettled, the heavy public expenditure involved, the need to keep rents to a minimum, and the high densities in existing private domestic accommodation-not to speak of the squatter huts which were being replaced-it was necessary and justifiable in the context of emergency housing.
59. By adjusting the positioning of the partitions in these blocks, the sizes of the rooms could be altered to meet the needs of those being resettled. For example, a full-bay could be turned into one larger room of 152 square feet and a smaller one of 86 square feet, while the standard basic room of 120 square feet could be partitioned or sub-divided to make smaller rooms for childless couples or for two or three individuals who were willing to live together. The result is that there are now in the old estates many different sizes of room, varying between 60 and 360 square feet (the latter being a special design of self-contained flat with its own kitchen, lavatory, shower and private balcony).
60. Early in 1964 the Architectural Office of the Public Works Department designed the first blocks of a new pattern (known as
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