THINK of the iconic picture-postcard village of Lavenham and people tend to imagine the historic Guildhall, great wool church or its row upon row of medieval cottages.

THINK of the iconic picture-postcard village of Lavenham and people tend to imagine the historic Guildhall, great wool church or its row upon row of medieval cottages.

Its sewerage is not, typically, the first thing to spring to mind.

But running beneath the heart of the village is a network of early drainage tunnels which - while not quite up there in the glamour stakes with Stonehenge and Hadrian's Wall - appear to be making the hearts of history buffs race just as fast.

The intricate web of tunnels might be concealed from view but the picturesque village's first plumbing system looks set to be registered as an ancient monument - to rank alongside some of the best-known landmarks in the country.

English Heritage experts have been investigating the drains that carried water and waste to and from the booming medieval wool centre, which helped fund the village's prestigious Tudor buildings.

The best example is a 500-year-old network of brick tunnels in Water Street, which are also thought to stretch under the timber houses and cobbled lanes of Church Street, Lady Street, Barn Street and Shilling Street.

Historians have put the culverts up for Scheduled Monument Status because they are a rare early example of municipal plumbing.

Until that period, sanitation was a rare and expensive luxury usually reserved for royal palaces but the wealthy merchants of Lavenham could afford it too.

Jane Gosling, chairman of heritage watchdog the Lavenham Society, explained: “Although the culverts aren't famous - it is a whole underground world which needs to be protected.

“They offer a glimpse into Lavenham's past as important as the timber-framed houses, which cover them.

“It was a huge building project for the time, necessitating the removal and re-erection of several houses in the then much wider Water Street. And there is evidence to suggest that they were left uncovered in parts and used as a private water source - a very early example of indoor plumbing.

“They are of great architectural merit and are in remarkably good condition. It is possible to walk or crawl through them for quite long stretches along Church Street, part of High Street and the entire length of Water Street.

“Past attempts to get these unique structures protected have failed, yet they are undoubtedly of national as well as local significance.”

Richard Ward, director of Suffolk Preservation Society, welcomed the plan and said he hoped the tunnels could be studied in more detail so films and exhibitions of the inaccessible culverts could help the public appreciate the little understood ancient network.

A spokesman for English Heritage confirmed the early drainage system was being considered for monument status but was unable to say when historians would be able finish their study and give their recommendations to the organisation's bosses.

The first toilet was invented in about 1700 BC at the Minoan Palace of Knossos on Crete, which featured four separate drainage systems that emptied into great sewers constructed of stone.

The Knossos palace latrine was the world's first flushing toilet but was lost for thousands of years.

The Roman's built great baths with water supplied by aqueducts from sources miles away, which could accommodate over 3,000 bathers.

The early Christians rejected bathing as synonymous with debauchery and vanity.

Some plumbing emerged in the medieval period but bathing didn't become popular again until the 19th Century - initially as a health pursuit.

In the 16th Century Sir John Harrington invented a “washout closet” but it would take a further 200 years before Englishman, Alexander Cumming, would patent the forerunner of the modern toilet.