SW1P: 537 of 749 postcodes stand below a spring high tide

The ground at 537 of SW1P's 749 postcodes (72%) 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 3.0 m and 4.5 m, measured from Ordnance Datum; the middle one stands at 3.7 m.
• 745 of 749 stand lower than the 1953 tide (5.41 m).
• 749 lie in the Environment Agency's Flood Zone 3 from the sea, mapped without defences.
• Mostly in Westminster; partly in Wandsworth.