Historical graph of UK national debt

This graph dates back to the 1690's when the Bank of England was first created.  Many economists and popular pundist are 'alarmed' at the current national debt of the United Kingdom.  Surpassing 50% as the nation is running a budget deficit of 12% of gdp.  Yet clearly the nation survived and prospered with much higher national debt levels in the past.  The UK was the main world econoic power in the 1800's, and had a national debt of 150% of gdp for a good period of that.

It seems strange but the national debt is really just something that balances the expansion or contraction of private credit.  In periods like the modern era, where there has been a huge and ever growing private credit expansion, the national debt is low by historical standards.  Now as the deleveraging in the private sector begins, the national debt must expand to keep the money supply going in the economy.