The method for generating time series design tide curves is given within the user guide contained within the supporting documentation: Coastal flood boundary conditions for the UK: update 2018, User report. A link is provided with the data on environment.data.gov.uk or can be found in the “doc” folder of downloaded data. Extreme sea levels and surge profiles are provided by the CFB. The UK Hydrographic Office, Admiralty and the National Oceanographic Centre supply astronomical tidal time series data for a range of tide gauges throughout the UK. There are also software packages available to derive astronomical tidal data from Admiralty and NOC.