Thanks to Jagjit Chadha, Amit Kara, Barry Naisbitt and Iana Liadze for helpful comments and suggestions. We also thank Nathaniel Butler-Blondel for compiling the database. Unless otherwise stated, the source of all data reported in the figures and tables is the NiGEM database and forecast baseline. The UK forecast was completed on 12 April 2019, more recent data is incorporated in the text.