Due to the recent boom in the housing market (spurred on by the governments help to buy scheme), the construction industry is now starting to grow at a rapid pace, so rapid that brick production cannot keep up. The accelerated growth in this sector has meant that the shortage of these building materials is a real concern for the construction industries.
The big house builders are consuming vast quantities of building materials, and tradesman leading to a shortage and helping to drive prices up. How sustainable this will be nobody knows, it is good news for the economy but could be bad news if you are looking at embarking on your own building project.
A local brick supplier had mentioned that certain kind of bricks are on a 25 week lead time, they still carry a lot of stock but it is definitely something to consider when you are planning building work which needs bricks.