Only Ireland fared worse, and there are fears that after Brexit, when the EU’s strict safeguards on water quality no longer have to apply, the situation could become worse.

Twenty measured sites around Britain's coast, representing 3.6% of the total surveyed, were found unsafe for swimming in the EEA’s annual survey.

Before it joined the EU Britain’s seas had earned it the nickname “the dirty man of Europe”, but complying with EU legislation improved the situation – even though the country continued to discharge raw sewage into its seas until 1998, longer than any other European country.

Should Britain relax the regulations again after Brexit in an attempt to make its industries more competitive, it is thought that it will run the risk of recriminations from the EU.

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