WC1X: 7.8 m clear of the highest tide in the London Bridge ledgers

The lowest postcode in WC1X, WC1X 0AY, stands 7.8 m above the highest tide in the London Bridge ledgers (5.41 m, 1 February 1953). The highest, WC1X 9HW, stands 30 m above it.
- Ground at eight in ten of its postcodes: between 14 m and 28 m, measured from Ordnance Datum; the middle one stands at 18 m.
- None lies in the Environment Agency's Flood Zone 3 from the sea.
- Mostly in Camden; partly in Islington.