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Improved methods and longer observed gauge data series have been used to produce the new extreme sea level information. This has led to differences compared to previous estimates.

Differences of less than 0.1m are not considered significant as these are within the accuracy of ESL estimation. Gauge locations with changes in level larger than 0.1m for the 200-year return period include Mumbles, Newport, Barmouth (Wales), Felixstowe and Cromer (England). Areas of greater change between gauge sites include the Severn Estuary, Solent, Solway Firth, Ornkey Islands, Pentland Firth and Liverpool.

The new levels have been validated against other statistical methods and extensively checked against local knowledge and information. The new levels provide the best available source of information extreme sea level information and so should be used in all flood risk management and decision making.

Lower and upper confidence levels are provided with all extreme sea levels and may be used to inform flood risk where there remains uncertainty.