Almost every British village with a river running through it has, at some point, had a mill. Some are still working, preserved by trusts or run as visitor attractions, but the majority have quietly slipped out of use and been converted into houses, workshops, or simply left to the water. The good news for anyone curious about their local history is that mills leave traces everywhere. You just need to know what you are looking for.

Start with the name and the map

Before you go anywhere near the water, do some desk work. Place names are extraordinarily stubborn. Mill Lane, Mill Road, Mill Street, Mill Hill, Mill Pond Close and The Old Mill are all still in use the length and breadth of the country, even where no mill has stood for a century. If your village has a road with "mill" in it, ask yourself what it was named after.

Then look at the Ordnance Survey. The large-scale county series maps of the late nineteenth century mark mills in some detail, often labelling them "Corn Mill", "Watermill", "Saw Mill" or "Fulling Mill", and showing the leat, the pond, and the tailrace. Compare a sequence of maps from different decades. Channels were frequently re-routed, straightened, or abandoned, and a mill that appears on an 1880s sheet may be marked "disused" by the 1900s. Layering historic maps against a modern one is the single most useful thing you can do before a site visit.

Reading the river itself

When you do get out on the ground, walk upstream of the suspected mill site first. A working watermill needs a head of water, and that head is usually created by a weir, a leat, or a pond. Look for:

• A leat or headrace — a channel leading off from the river, often running roughly parallel to it at a slightly higher level. These can be silted up, overgrown, or reduced to a faint terrace in a field, but they are usually still visible once you know to look.
• A millpond — now often a duck pond, a fishing lake, or simply a damp hollow full of reeds. Check the shape: artificial ponds have unnaturally straight sides.
• A weir — some are Victorian concrete, some are older timber-framed structures, and some are just a line of stones across the bed. A weir with no obvious purpose is very often a mill weir.
• A tailrace — the channel returning water to the river below the mill. Look for a straight, fast-flowing section rejoining the main stream.
• An island or a split channel — the classic arrangement where the river was divided to feed the mill while the rest continued past.

The leat is often the giveaway. It survives long after the buildings have gone because it is a feature in the landscape, and it will usually still hold water or show as a damp line in a field.

Bricked-up wheel pits and other masonry clues

The wheel pit is the heart of the mill, and it is surprisingly durable. It is a stone or brick-lined pit, often several feet deep, built to house the waterwheel. When a mill was converted, the pit was frequently filled in, capped, or bricked up rather than demolished.

Look for a straight vertical wall face where it has no business being, particularly where a building sits close to a river. Look for blocked arches in the base of walls, ventilation grilles, or a puzzling cellar-like space. Sluice gates and their frames are often still in place too, rusted into position. Ironwork tends to survive: a heavy sluice gate, a set of gear teeth, a bearing block, or a shaft protruding from a wall are all strong indications of a former wheel.

And then there are millstones. These turn up everywhere. They are reused as paving slabs, gateposts, doorstep steps, garden ornaments, or walled into outbuildings. A chunky round stone with a square hole in the middle, sitting by someone's front door, is very likely a millstone doing a second career.

Local archives and what they hold

This is where the story really comes together. County record offices, local studies libraries, and archive centres hold far more than most people expect. Worth asking for:

• Tithe maps and apportionments (mostly 1830s–1840s) — these name the mill, its owner, its occupier, and the land around it.
• Enclosure awards and maps, which sometimes show watercourses in unusual detail.
• Estate maps from the eighteenth and nineteenth centuries, often beautifully drawn and showing leats, ponds and weirs.
• Sale particulars — when a mill changed hands, the auction catalogue often included a plan and a detailed description of the machinery.
• Newspapers — local papers reported mill fires, floods, accidents, and sales. A single report can name the miller and describe the wheel.
• Trade directories — a run of directories will tell you when a miller disappears from the listings, which is often when the mill stopped working.

Ask the archivist specifically about maps showing former river channels. Rivers have been moved, straightened and embanked for centuries, and the mill often sat on an older course that no longer exists. A comparison of a tithe map with a modern survey can reveal a channel that was diverted to serve the mill and never put back.

Putting the pieces together

A mill's history usually follows a recognisable arc. It starts as a manorial or monastic mill grinding corn for the village, sometimes with a second function such as fulling cloth or grinding bark for tanning. It is rebuilt in stone or brick in the eighteenth or nineteenth century, gains iron machinery, and then loses its economic footing. Steam and roller mills in the towns take the trade. By the early twentieth century it is disused, and by the mid-twentieth it is a house, a store, or a ruin.

What makes tracing it satisfying is that the evidence is layered and local. A leat in a field, a blocked arch behind a garden wall, a millstone on a doorstep, and a name on a tithe map all belong to the same story. Take photographs, sketch the layout, make notes on the map, and talk to the people who live there. Villagers usually know more than the records do, and they are often delighted that somebody has finally asked.