A nice set of tongs, they have a double thread pattern and shell bowls. In very good condition, they were made by Scottish Provincial Silversmith, Robert Keay in Perth. He was working between 1791 and 1825. They measure approximately 15cm long.
(For another pair of a similar shape, check out http://www.silversugartongs.com/Perth/Robert%20Keay%20I%20BC.htm)