WC2N: one of 139 postcodes stands below a spring high tide

The ground at one of WC2N's 139 postcodes, WC2N 6NU, is lower than an ordinary spring high tide at London Bridge (3.9 m above Ordnance Datum).

• Ground at eight in ten of its postcodes: between 5.1 m and 19 m, measured from Ordnance Datum; the middle one stands at 10 m.
• 19 of 139 stand lower than the 1953 tide (5.41 m).
• 12 lie in the Environment Agency's Flood Zone 3 from the sea, mapped without defences.
• Mostly in Westminster; partly in Islington.