Here’s a mystery.

I have my own theories, and admittedly have the advantage of the data to test them, but I was wondering if there are any of you out there who have any views as to what might lie behind this rather surprising effect of the credit crunch.

I will refrain from contaminating your thoughts with my suspicions other than to say that the analysis I have been doing leads me to suspect a combination of factors, but…

Here is the poser: How come average planning times for residential schemes approved in the months after September 2007 rose so sharply when the number of planning applications began to fall?

I am busily doing some analysis for the Housing Market Intelligence report using data provided by Barbour ABI planning data.

As you might imagine I was rather taken aback when I plotted this chart.

And as Andrew Whitaker, the-ever-helpful-on-such-matters Planning Director at the Home Builders Federation, agreed when I sought his thoughts: “What an amazing spike!”

Just a bit of background. what is being measured here is the time taken in weeks from application to approval of residential schemes of 10 units or more approved within each quarter.

The horizonal axis represents the date of approval, so we are looking back at the how long ago it was when the application was recorded.

I have checked the data for anomalies as best one can. That and other tests have led me to a reasonable level of satisfaction that the phenomenon is real.