AN unexpected historical discovery has been made at Scottish Water's site at Glencorse, near Penicuik — a Roman marching camp nearly 2000 years old.
The revelation has provided another clue as to how the Romans organised their occupation of the Lothians.
It had not been confirmed whether the site was, in fact, a Roman marching camp, which had previously only been suggested by aerial photographs.
Scottish Water's stakeholder manager for the Glencorse Water Treatment Works Project Kenny Naylor said: "We carry out a detailed site investigation on all sites as a matter of course, and found a change in the soil when we were digging the ground.
"We quickly contacted the regional archaeologist who was able to confirm the existence of a Roman marching camp on the site."
It is believed the site, which is part of a network of other bases, watchtowers and camps across lowland Scotland, was situated to guard a gap in the Pentland Hills to the northwest of Flotterstone and the line of an east-west Roman road which skirted the foothills of the Pentlands.
The importance of the site in terms of the Romans in Scotland is crucial as it is unique in this area.
Senior project manager for Scottish Water Richard Anderson said the treatment works have now been relocated to retain the archaeological feature, but stressed the discovery of the site will not have a significant impact on the progress of the project.
Mr Anderson said: "We are encouraged by the response of residents and neighbours who attended the public open day last week.
"Clearly, Scottish Water's approach to preserving this archaeological feature is in harmony with the wishes of local people and the regional archaeologist."
David Connolly, development control archaeologist for Midlothian Council, said: "This preservation work by Scottish Water has given us an important insight into the Roman history in the Penicuik area."
He added: "Understanding the Romans in Scotland is a complex matter, as Scotland was not subjected to a single phase of occupation or conquest.
"Every new discovery leads to further understanding of Roman Scotland, and with the confirmation of the Glencorse site we have another important piece of the jigsaw."