ONS has wanted for some time to make historical UK national accounts data more easily accessible to researchers. This would match the standards of provision of other statistical offices, such as those in the Netherlands and the US. Restoring the broader UK historical macroeconomic dataset, along the lines of the discontinued Economic Trends Annual Supplement, was also felt to be highly valuable, especially the provision of quarterly and monthly macroeconomic time series over the past hundred years. The first aim of the project was to draw up an inventory of existing historical national accounts data and other macroeconomic and financial time series covering the past hundred years. Where possible, the data has been made available in spreadsheet form for researchers to use. With the inventory established, the next aim was to take a view of whether (and how far back) it was possible to construct a comprehensive set of historical national accounts data consistent with the existing ESA10 system of national accounts. ESA 10 (The European System of National and Regional Accounts) is the newest internationally compatible EU accounting framework for a systematic and detailed description of an economy. The vast majority of ESA10 national accounts series only began in 1997.