Hamish Mowatt originally discovered the tomb by the car park of the Skerries Bistro, at Banks, in 2010.
Speaking to The Orcadian newspaper this week, Mr Mowatt explained that last month he employed the services of a Canadian archaeologist, over a four-week period, to excavate the tomb’s central passageway down to floor level. It was during this work, said Mr Mowatt, that a lintel stone was discovered directly underneath the entrance, leading to what appears to be a further chamber below. This sixth chamber has yet to be excavated.
A number of discoveries were also made in the central chamber of the tomb last month, including more human remains, various fragments of pottery and a piece of antler.
Now that the passageway has been opened up, visitors can gain access to the tomb and see inside it for themselves. Mr Mowatt also has a CCTV camera set up inside, allowing visitors to view the interior from an external viewing area.
Other work carried out at the site included the reinstatement of one area of the tomb, and the replacement of cut stone to lay over the structure to protect it from the elements.