I agree that a ratio to disposable income would be more relevant, but I dob't think such a ratio exists or would be easy to put together. Interet rates are also an important factor and in the mid 90s the BoE had rates at about 6%.
At the peak of the Irish housing boom the income to house price ratio was about 8.6 (€310,000/€36,000). Today it is at about 4.6 (€157,000/€34,000). And that decline has happened despite record low interest rates. What do you think will happen when, not if, interst rates start rising towards historic averages?
The unfortunate truth is that interest rates and taxes are only going in one direction.