Figures compiled by EBS Building Society and economic consultants DKM show that average first-time house buyers are paying a smaller proportion of their income in mortgage repayments compared with a year ago.

Their affordability index measures the amount paid by a first-time buyer couple, assuming each is on average earnings, buying the average-priced new house, and that their mortgage is worth 90% of the value of their property.

On this basis, they say the average couple was spending 8.8% less in mortgage repayments in December compared with December 2006. As a percentage of income, repayments fell from 26.4% to 22.6% over the same period.

EBS and DKM say the index takes account of changes in interest rates, mortgage relief, house prices and average earnings. They point out that average house prices fell by around 6% over the year, while Budget changes in mortgage relief also affected the figures.