East Finchley is almost untouched by river and sea flooding, and its flood risk comes from rain that cannot drain away fast enough. Hardly any postcodes fall in the river-and-sea flood zones. About a quarter score high on at least one of the wider flood measures. No flooding is on record. The risk is real, and it comes from overhead.
In the Environment Agency's river-and-sea flood zones, about 1% of East Finchley's postcodes are in zone 2 and under 1% in zone 3. Zone 3 is the higher-probability band. Zone 2 is the medium-probability fringe outside it, so the two shares are separate slices and neither contains the other. For a district in North London, the rivers have left it alone.
On average, homes here are about 800 metres from the nearest water. The trouble comes from heavy rain on roofs, roads and paved-over front gardens, with the drains taking it away only as fast as they can. Surface water collects in dips and low spots, and those can be one street or one house apart.
When the Environment Agency adjusts its zones for climate change, about 2% of postcodes fall inside them. That is a modelled view of where the river-and-sea zones could move. It is a small number, and it tracks rivers and the sea, which are the two things East Finchley has least to fear from.
Insurers look at each address. An insurer will see the surface-water mapping for the exact property, so a house on a street that never floods can still cost more to cover if it is in a low spot. Get an indicative buildings-insurance quote on the specific address while the survey is being arranged, so the premium is known before the mortgage offer is.
Across all of East Finchley's postcodes, about 25% rate high on at least one flood measure, about 17% medium and about 26% low. Surface water is one of the measures counted alongside rivers and sea, so a postcode only has to rate badly on one of them to be included. That explains why the figures are so far above the flood-zone shares. Each set of figures measures something different.
Within the Environment Agency's modelled high-probability flood extent, no postcodes are undefended and about 0.2% are defended. "Defended" means only that the model includes a defence. It does not mean the house is safe, and the share is too small to tell a buyer much. A defence in the model has little to do with the rain that causes the real problem here.
The nearest tide gauge is at Portsmouth, where sea level rose by about 2 millimetres a year between 1962 and 2023. The sea is a long way from East Finchley.
The Environment Agency has no recorded flooding anywhere in the area. That is reassuring, though only floods that were reported get recorded, and surface-water flooding often clears from a road before anyone writes it down.
East Finchley's flood risk is below par. Nearly all of it comes from rain on a built-up hillside, and the river-and-sea zone maps will not show a buyer any of it.