Link fixed. Photo is up in the original post.

This is really dark for me to be able to tell with any certainty.
There is no Gilchrist Tartan listed with The Scottish Register of Tartan.

The MacDiarmid Tartan.



With this description:
"MacDiarmids are a sept of Clan Campbell. The tartan was first published by W & A.K.Johnston in 1906, in 'The Tartans of the Clans and Septs of Scotland'. The author, H. Whyte, introduced many previously unrecorded tartans including 'Dress' and 'Hunting' tartans of both clans and septs of clans. This is the version woven by Lochcarron & House of Edgar (December 2004)."

As MacDiarmid are a sept of Campbell this could be lighter version of Black Watch.



With this description:
"The tartan is thought to have been designed at the time of founding of the 43rd (later named) the Black Watch in 1739. It was adopted as the Campbell clan tartan in the early 19th century. This tartan is worn by the present Duke of Argyll, who has approved the sett. The present Black Watch tartan is the same sett but dyed in darker shades."