The UK’s economy crashed in 2008 in large part because the Bank of England and the Treasury allowed it to crash by allowing nominal gross domestic product to crash below trend. It stays depressed because the Bank of England and the Treasury have not acted to return nominal gross domestic product to trend.
See this graph. See the disaster then the depression. We are almost growing at our trend rate again, but are nowhere near our trend level. This is the main reason things suck and I will be focusing on this more monomaniacally on this from now on.