"A number of workmen in trenching a piece of waste land to the north of Largo, have turned up human remains. The bones, with skull pointing to the north, mouldered down on exposure to the air. They were encased within a rudely-formed cist of flat stones loosely placed together, and the body seemed to have been interred in a sitting posture. From time to time several similar discoveries have been made in and about the same part of the country."
The "similar discoveries" mentioned included various finds made during the construction of the railway in the 1850s, including 15 cists. The advantage of the 1965 excavations was, of course, that scientific progress allowed very detailed analysis of the findings. Plus, the careful cataloguing and storage of the finds made then have allowed subsequent tests to be run on them more recently, as techniques have continued to advance.
In brief, the 1965 dig found part of a cemetery which contained both square and round cairns (six in total), five long cists and two more complex burial structures. A 'cairn' is defined as a mound of stones built as a memorial or landmark, while a 'cist' is an ancient coffin or burial chamber. It was concluded that this burial ground had been in use for a period of more than a century. Radiocarbon dating techniques suggested usage between approximately AD 450 and AD 650 (more recent than initially thought). The two complex burial structures were referred to as the 'Dumb-bell Complex' and the 'Horned Cairn Complex'. These structures each contained multiple cists and had clearly been built with great care. A mix of male and female skeletons were found - 22 in all and these were thought to range in age from 18 years old to between 35 and 45.
A very full and detailed paper of the findings of the 1965 dig can be viewed at:
http://archaeologydataservice.ac.uk/archiveDS/archiveDownload?t=arch-352-1/dissemination/pdf/vol_130/130_585_636.pdf
...this paper contains several photographs and illustrations of the site. I find it very hard to imagine what life might have been like for the people who populated this area at that time but clearly this particular site was important to them. The sheltered bay, the bounty of the sea, nearby fresh water supplies and terrain which is easily travelled over were, and still are, factors which make this area a good place to be.