Not from the sea, which is the thing everyone assumes. Almost nothing here sits in the river and sea flood zones. Nearly one in five postcodes still carries a high rating on some flood measure. The village runs down a valley to a cove, and water has always gone downhill for a living. The Atlantic is not the problem. The rain arriving from above it is.
Start with the river and sea zones, because they are the ones that turn up in conveyancing. The Environment Agency's mapping puts about 2% of the area's postcodes in flood zone 3, the higher-probability band, and none at all in zone 2. Those two zones are separate bands rather than nested circles, zone 2 being the additional medium-probability fringe lying beyond zone 3, so a zero there is not a gap in the data. It means the modelled river and sea flooding stops abruptly at the edge of a small area and does not spread out into a wider margin.
Which leaves surface water, and that is a different animal in a place shaped like this one. Roughly 1% of postcodes fall inside historic flood extents, and the recorded flood history amounts to a single event in October 1988, attributed to an ordinary watercourse rather than a river or the sea. One event in the record is not a reassurance so much as a description of the type of flooding on offer here: sudden, local, coming off a hillside, and unlikely to give anybody much notice.
Adding the climate allowance does not change the shape of it. The climate-adjusted zone share stays at about 2% of postcodes, so the forward-looking river and sea picture and the present one are effectively the same map.
For insurance, that split matters more than the headline. Properties outside the zones generally price without much fuss, while anything inside a modelled extent or with a surface-water history should be quoted before an offer goes in rather than after. Insurers read these maps at address level, not village level, and the answer for the house at the bottom of a valley will not be the answer for the one on the Beacon side.
Across all indicators taken together, including surface water, about 18% of the area's postcodes carry a high rating on at least one measure, 12% a medium rating and 31% a low one. Those bands overlap with the zone figures above rather than sitting alongside them, so they are a wider net, not an additional set of problems.
Counted as homes, the Environment Agency's rivers-and-sea mapping lists 268 properties across the postcodes that carry any risk at all, of which 43 are at high risk, none at medium and five at low. Only postcodes with some risk appear in that list, so the total is the exposed population rather than the village. Nineteen of the high-risk properties are residential.
On defences, roughly 2% of postcodes sit within a modelled high-risk extent where a defence is present in the model, and the same share sit within one where none is. A defence in the model describes what has been built, not what will hold, and nobody should read it as an all-clear.
The coast itself is closer than the flood zones suggest. About 10% of postcodes lie within 500 metres of the shore, the nearest gets to within 25 metres, and the median distance is around 1,150 metres. Every postcode in the area falls under a shoreline management plan, and the stated policy over the next 20 and 50 years is no active intervention, moving to no active intervention or managed realignment over 100 years. That is a statement of intent about maintaining defences, not a defence, and no active intervention means precisely what it sounds like: the cliffs are expected to do what cliffs do.
At the nearest tide gauge, at Devonport, sea level rose by about 2.35 millimetres a year over the record from 1962 to 2015. That is a measured historic rate, not a projection.
Flood risk is among the weaker parts of the case for St Agnes, and the weakness is entirely in the surface-water column rather than the one with the sea in it. Buy here and read the address-level map for the specific house, because the village average will tell you almost nothing about the bottom of a valley.