An official report completed in 2008 for the development of Kai Tak identified the area north of where Sacred Hill once stood as having "high archaeological potential" - just seven months before the MTR Corporation announced it would build a station there.
Work on the To Kwa Wan station of the Sha Tin-Central Link has recently been affected by large-scale historic discoveries, but the emergence of the 2008 report suggests such discoveries could have been foreseen.
The report by the Civil Engineering and Development Department was completed in October 2008, after an archaeological excavation exercise which took place between March and June to ascertain the heritage value of the wider Kai Tak area before development.
The report said the excavation "produced evidence for what may well prove (with further research) to be a regionally important site of Song/Yuan dynasty date - the area immediately to the north of the former Sacred Hill has been proven to be of high archaeological potential".
This conclusion was based on Southern Song or Yuan dynasty ceramics dug from a trench northwest of the current excavation site. The paper recommended further study to determine the full extent of the relics.
Despite the discoveries, the MTR Corporation announced in May 2009 the To Kwa Wan station would be built on the site. Previously, it had planned to build the station near the Hong Kong Society for the Blind's workshop, less than a kilometre away.
It said the new location could better serve residents because it was closer to Kowloon City.
A further archaeological report in 2011 concerning the construction of a pumping station next to the former Sacred Hill site also suggested the area contained archaeological deposits that could date back to the Song dynasty. It was following this report that the railway project's environmental impact assessment recommended the present excavation, which has produced a vast trove of relics dating back more than seven centuries.
Tim Ko Tim-keung, a local historian and a member of the Antiquities Advisory Board, said the archaeological importance of the site had been overlooked and he feared the preservation of relics could be compromised because construction on the new station had already begun.
"Unfortunately no one paid attention to Hong Kong history. If the railway station was about 100 feet further southeast it would be the Sung dynasty coastline and the clash with the relics could be avoided."
Conservancy Association director Dr Hung Wing-tat, a transport expert, said it was not too late to look for alternative alignments of the railway. "The excavation is exactly being done to meet environmental impact assessment requirements… If the Antiquities and Monuments Office considers the heritage site should be conserved in situ, it is possible to change the plan."
Members of the Antiquities Advisory Board yesterday visited the excavation site.
Responding to accusations that some relics had been destroyed, board chairman Andrew Lam Siu-lo said that the removal of relics dating from more modern times was to make way for deeper excavations that could uncover more ancient items.
A spokeswoman for the MTR Corporation said it was studying ways to adjust the construction project, including re-sequencing tunnel boring works.
Sacred Hill, which stood in what is now To Kwa Wan, was also once known as Hill of the King of the Sung. The hill was levelled during the Japanese occupation of Hong Kong in the 1940s as part of the extension works for the former Kai Tak airport.
The place is well known for one of Hong Kong's most important monuments, Sung Wong Toi, a stone with carvings indicating it once sheltered two 13th-century emperors. The remaining portion of the boulder is now located in Sung Wong Toi Garden, Ma Tau Wai.