Gamlingay does have a flood risk, but it comes from rain, with no river or sea anywhere near it. None of the village is in the river-and-sea flood zones. About one postcode in seven still carries a high flood rating. The water falls on ground that drains slowly and runs off along the lanes. Neither the river nor the sea is the problem here. The rain is.
The Environment Agency's river-and-sea flood zones take in 0% of Gamlingay's postcodes. None is in Flood Zone 3, the highest-probability band, and none is in Flood Zone 2, the medium-probability band just beyond it. The lowest ground in the parish runs along the Millbridge Brook, and the mapping doesn't rate even the brook as a flood risk.
Surface water is a different matter, and the zone maps don't show it. Much of the central parish is on the Lower Greensand, where heathland drained so badly that quaking bogs formed on Gamlingay Heath and Cinques Common, and the heath bog was only drained in 1855. With the river-and-sea zones empty, the postcodes rated high here are being flagged by other measures, surface water among them. The Environment Agency's long-term flood risk service shows surface water street by street, and that layer for the exact postcode is the one to read. Rain that once kept a bog going now lands on patios and driveways.
The Environment Agency's climate-adjusted flood zones, which allow for heavier future river flows, also take in 0% of Gamlingay's postcodes. On that measure the rivers stay out of the picture, and the adjustment doesn't touch the rain falling on the greensand.
Clean river-and-sea mapping counts in Gamlingay's favour when insurers quote. Insurers also check surface-water mapping, though, and a house on one of the high-rated postcodes may find that in the price of its cover. The insurer reads the surface-water map even if the buyer never does.
Across Gamlingay's 66 postcodes, about 15% rate high on at least one of several flood measures, 18% medium and 52% low. Those measures include surface water alongside rivers and sea, so a single high reading on any one of them is enough to set the rating. Two neighbouring postcodes can be rated quite differently.
The Environment Agency's modelled flood extents put 0% of Gamlingay's postcodes in the high-risk area without a defence, and 0% in it with one. With no river flood modelled, there is nothing for a defence to hold back. No flood wall stops rainwater running down a lane.
The Environment Agency records no historic flooding in the area. That is good news, but only as far as it goes. The record holds what was reported and mapped, and water across a back garden rarely gets that far.
Rivers and the sea pose no threat to Gamlingay, but the rain does, and with about 15% of postcodes rated high on at least one measure, the flood picture here is weaker than most buyers would assume.