A poster once actually did the maths on this and I saved it. This is what she posted.
In 1970, average gross weekly wages for men and over 21 were £28 and £14, respectively. Even if a household had two earners, which was rarer, the average weekly wage was £42 for a gross annual wage of £2184 or £182/month. Before taxes.
The average house cost about £11,500 and required a 5% deposit. Even with a big deposit you would have around a £10,000 mortgage. A 15% interest rate means annual payments of £1500 or monthly payments of £125. That mortgage payment is 68.6% of the gross household pay.
Now a modern example: Numerous online banking guides inform me that usually you can only get a mortgage for five times household salary, let’s make it six to be fair.
In the example of a £300k mortgage, then, gross salary is at least £50K, monthly salary is at least £4167. At 5%, payments are approximately £15,000 per year or £1,250 per month.
Mortgage payments are just under 30% of gross household pay. Less than half the 1970 example.
Now bear in mind that there were no fixed term mortgages and if the bank rate went up your mortgage followed the next day.