I congratulate my hon. Friend Ms Ghani on securing this Adjournment debate and on putting her case very strongly, and rightly so because it is such an important part of her constituency. Michelham Priory is, as she says, a grade I listed building. It is one of our foremost Augustinian priories, with a rich history, stretching back nearly 800 years. With its grade I listing, it boasts Britain’s longest continuous medieval water-filled moat, which is quite something actually, because only 2.5% of England’s 400,000-plus listed buildings are classed as grade I, so it is special.
I agree with my hon. Friend that it is essential that we do what we can to protect the historic environment, including the priory. As she mentions, the Environment Agency over many years has held many meetings with the Sussex Archaeological Society, the owners of the priory, to discuss matters of water management relating to the priory. Those conversations started long before my hon. Friend came to this place. Nevertheless, I understand that a key concern of the Sussex Archaeological Society has been to avoid flooding the priory grounds in the winter and drying out the moat in the summer—something which obviously has deterred the holding of events at the priory, which provide important income for the society. It is the Environment Agency that has to manage the water control structures to reduce that flooding aspect—that is one of the key areas that comes under its hat. Unfortunately, because of the wide expanse of the moat, fed by high flows through channels in the winter, salty river deposits have built up naturally. I have been told that at the moment the moat is 80% filled with silt. That can result in its drying out in the summer months, and there is a risk that the moat will be lost to posterity if it is not looked after, as my hon. Friend says.
To prevent the moat from drying up, in the past, the Environment Agency operated the upstream controls to divert the Cuckmere river into the moat, but that approach created an impassable barrier to fish, so it had to cease. My hon. Friend has not mentioned that then there appeared in the moat a plant called floating pennywort, a non-native invasive species that grows incredibly rapidly and is responsible for swamping waterways, blocking water flow, clogging up water channels, crowding out native plants and taking oxygen from fish and insects. It is not found anywhere else on the Cuckmere river. The landowner, the Sussex Archaeological Society, has a duty to prevent the spread of the infestation, and diverting the river through the moat in the summer months would have increased the chances of the plant’s escaping into the wider river environment. To intentionally do so would be classed as a criminal act. That is one of the big dilemmas of the situation.