Dark, dank and once likened to a “loo that hasn’t been flushed for 500 years”, delving into the bowels of Paisley Abbey may not sound like a particularly pleasing way to spend a summer’s afternoon.

The Abbey Drain, with its vaulted stone ceiling overhead and stream of sludge underfoot, offered medieval monks and royal visitors a discrete means of disposing of their particularly personal ‘business’.

Of course they may have expected that what went down the drain would, if not stay there, at least be sent on a journey never to pop up again.

However now an area around the drain is to be opened up in a bid to uncover just what may have been flushed away centuries ago.

Funding has been secured for an archaeological dig which will see trenches created above the drain, enabling the public to join experts sifting through the soil in search of artefacts linked to the Abbey’s rich history.

It’s hoped the “Wee Dig” in September will expand on what is already known about Paisley’s monastic past, as well as inspiring budding archaeologists of the future.

Renfrewshire Council has been awarded £10,000 from the Heritage Lottery Fund’s (HLF) Stories, Stones and Bones programme as part of the Year of History, Heritage and Archaeology to conduct the dig, which links with the town's bid to become UK City of Culture in 2021.

Iraia Arabaolaza of Guard Archaeology, which is managing the event, said exploring the trenches around the drain is likely to throw up fascinating glimpses of how mediaeval monks went about their daily business.

“In the past we have found easily identifiable items, like jug handles and pottery which we can trace back to places like France,” she added. “It all helps us gather information about how they lived centuries ago.”

At more than 700 years old, the Abbey is renowned not only for its outstanding architecture but also as the cradle of the Royal House of Stewart, with a number of the Stewarts buried within its walls. It is also believed that Robert II, the first Stewart king of Scotland and the grandson of Robert the Bruce, was born within the walls of Paisley’s Abbey. .

The Abbey’s drain, which is unique to Britain, was built by master craftsmen sometime in the 14th century. It stands up to two metres high in parts and three and half feet wide.

A stretch almost 100m long was rediscovered in 1990, when an initial excavation found several hundred fragments of pottery, musical notes scratched onto slate, dice and gaming tokens, tuning pegs for musical instruments and lead seals.

Included in the haul was a complete chamber pot, which was later put on display in the Abbey sacristy, and the remains of more than 140 plants, believed to have been used by the monks for medicine.

A further excavation the drain in 2009, prompted archaeology professor Steven Driscoll to praise it as being ‘uniquely well preserved’. "What's unusual is that it hasn't been messed with,” he said at the time. “This is a loo that hasn't been flushed for 500 years. We have a kind of sealed environment, containing artefacts like the earliest known piece of Scottish music, which we found scratched into pieces of slate.”

Ms Arabaolaza said that although it’s not possible for amateur archaeologists to enter the actual drain, the trenches are likely to reveal ‘treasures’ which have remained covered for centuries.

“The main aim of the project is to try to get people interested not only in archaeology, but in that area of Paisley, and the heritage and culture that’s there,” she added.

Councillor Iain Nicolson, Leader of Renfrewshire Council, said: “The ‘Wee Dig 2017’ is a very exciting project which celebrates our unique heritage - one of the main themes of our Paisley Town Centre Action Plan 2016 – 2026 which aims to regenerate the town centre and create jobs.

“This project demonstrates how we are delivering on these plans by making the most of our assets to attract more people and businesses into the town.”

A film on the Paisley Abbey Drain will allow visitors to see what is under the area of the dig site.

Reverend Alan Birss, Minister for Paisley Abbey said: “It is good that the dig will have a strong community focus as the history of Paisley is so closely interwoven with the Abbey’s history. The Wee Dig will give everyone the opportunity to become detectives investigating our shared past.”