This is the core of the problem; the government has lost control of the public purse.
This chart compares just one month's fiscal deficit - April - over the four previous years. During the good times, the government ran up a surplus in April. Revenues were always higher than expenditures.
Things began to go pear-shaped in 2008, but even then, the situation was under control. However, in April 2009, the government ran up a deficit of almost ₤7 billion. As the chart so amply illustrates, this monthly deficit is unprecedented.
Finally, the credit rating agencies have woken up to this unfolding disaster. At last, they have realised that the truck is rolling down the mountain track, and there is no one in the driving seat.