Shenley has no river or sea flood risk, but surface water is a real problem on parts of it. None of the village is in the river-and-sea flood zones. About one postcode in six still carries a high rating on at least one flood measure. Rain that can't drain away causes the trouble here. The official zone map is clear, but the full set of measures says otherwise.
On the Environment Agency's river-and-sea mapping, 0% of Shenley's postcodes are in flood zone 3, the highest-probability band, and 0% are in flood zone 2, the medium-probability band outside it. No river or coastline threatens the village on that measure. If your only flood question is about a river, the answer is no.
Surface water is a different measure, and the zone map doesn't include it. It covers rain that collects in low spots and runs off along roads and gardens because it has nowhere to go. That's the risk on the Shenley streets that do flag up. The parish made tiles and bricks for centuries because the ground is full of clay. Clay that's good for bricks doesn't soak up much rain.
The Environment Agency's climate-adjusted zone, which models how the river-and-sea zones could grow under a changing climate, also covers 0% of Shenley's postcodes. On rivers and the sea, Shenley stays clear even in the projection. The projection is modelled, though, and surface water isn't part of it.
For insurance, that split matters. A clear river-and-sea record helps, but insurers look at surface-water risk too, and a street with a high surface-water rating can still get a dearer quote or tighter terms. Get an indicative quote on the exact address early, because two houses a few roads apart in Shenley can be very different risks.
Combine the measures, surface water included, and about 16% of Shenley's postcodes are rated high on at least one, about 18% medium and about 35% low. A postcode counts if any one measure flags it, so the shares show how widely the village is touched, not how likely any single house is to flood. The full set of measures picks up streets the zone map leaves out, which is where the two maps disagree.
The Environment Agency's modelled flood extents put 0% of Shenley's postcodes in the high-risk extent, with or without a defence in the model, and 0% in the low-risk undefended extent. Those extents model river and sea water, so they back up the zone picture. A "defended" result would only mean a defence appears in the model. Here the question doesn't come up, because the modelled water never reaches the village.
The nearest tide gauge in the records is Portsmouth, which measured sea level rising at about 2 millimetres a year between 1962 and 2023. That's a rate recorded on the south coast. For an inland Hertfordshire village it's background, not a threat at the door.
No historic flooding is recorded across Shenley's postcodes. That's reassuring, because flood records tend to remember the worst events. It only covers floods that were recorded, though, and surface-water flooding on one street often doesn't make the records at all.
On rivers and the sea, Shenley is as clear as a village can be. Surface water is the weaker side, and the measures that include it flag enough of the village to put its overall flood risk on the poor side of average.