In 1981 Mrs Thatcher decided to cut spending. 364 economists wrote to The Times telling her she would exacerbate the recession. They were wrong. Interest rates fell, and economic activity took off.
Cameron could take heart that many of his policies involving a shrinking state sector will enable Britain to grow faster also. The end of the Euro will shatter the arrogance of the EU, and many repatriations of powers could become politically possible at the same time. Recessions often blow in the right changes, and this one will be no exception.