These data are forecasts of quarterly GDP and the consumer price deflator by the National Institute of Economic and Social Research.
The forecasts range from the one-quarter backcast (suffix l1_niesr) to the 5 quarter forecast (suffix 5_niesr), 1964 - 1982
NIESR data used in Aikman, David L., Oliver P.H. Bush, and Alan M. Taylor (2018). "Monetary versus Macroprudential Policies: Causal Impacts of Interest Rates and Credit Controls in the Era of the UK Radcliffe Report", NBER Working Papers 22380