The original planning was roughly on the basis of twelve dwellings per acre. That was tightened up to about fifteen to sixteen later, mainly through Government control of finance, pressures were brought to bear not to produce a density, but to use the money in the best possible way to secure as many dwellings as possible.
The Master Plan was prepared which laid down the confines of the various residential areas, the industrial areas, the town centre and the residential areas, as far as Stevenage was concerned it was six neighbourhoods and they were roughly to house a sixth of the ultimate population which in those days was 60,000, in other words 10,000 each. Then on a later revision the population went up to 80,000.
The tightening up of density as it were rather offset the population problem. You see what happened, was that after the war as you know, the population rose steadily but 1963/4 we reached a peak and it started turning down. The average occupancy rate was 3.5 persons to the dwelling up to about 1965 and the Government and practically a lot of the towns used their general statistic to make plans. Now that population occupancy rate dropped to about 2.5, it dropped one, and the trouble was to house a target population of X you had to have more houses because there were less people in the house.
Originally it was 3.5 and it dropped down to 2.5. Of course the trouble is until you get a census sorted – even in a mini census of that sort – you can’t tell when this is going to happen and it’s usually two or three years afterwards or even more, five years afterwards that you suddenly come to realise that your planning for 3.5 is off beam and you’ve got to do something.
There was a mini census in 1966 and it wasn’t till 1966 that the trend made itself felt, and it wasn’t till 1971 until that trend was very very severely confirmed and then of course we planned for the lower occupancy rates, but it was a bit more intricate than that, the method of calculation of population projection is the same as the one adopted by the Office of Census and Surveys, the cohorts survival system, that’s the way it’s done. Mathematically it’s a bit intricate, but mind you that goes wrong. As you know the census’ calculation goes wrong and they use absolutely the latest techniques, you can’t budget for human beings doing the things that they’re supposed to do ad infinitum.