Hi,
I found this "1865 JAMAICA ALMANAC" which shows which miltary were in Jamaica in 1865 which includes the 2nd Battalion, 6th Royal Regiment.
http://www.jamaicanfamilysearch.com/Members/a1865_08.htmAlso, a long read but interesting, written by Thomas FAUGHNAN, Late Colour-Sergeant, 2nd Battalion, 6th Royal Regiment. It contains the dates of when and where they were in the relevant time period.
https://www.gutenberg.org/files/51595/51595-h/51595-h.htm26 Feb 1858 "we proceeded by rail to Aldershot"
18 May1858 "from South Camp to Farnborough Station, where we took the train for Portsmouth." + "embarked on board H.M Ship "City of Manchester"
25 May 1858 Arrived Gibraltar
25 June 1862 embarked H.M.S. Himalaya.
26 June 1862 for the island of Corfu.
01 Jul 1862 Arrrived Corfu
This man was then stationed at Santa Maura.
04 Mar 1864 H.M.S. Orontes for Jamaica, in the West Indies.
18 April 1864 Arrived Jamaica
01 April 1867 Embarked on board the "Tamar" for Cork.
09 May 1867 Arrived at the Firth of Forth
"The 2nd Battalion 6th Royal Regiment was stationed in Edinburgh Castle over twelve months, when they got the route for Aldershot camp on the 30th May 1868."
So John YATES would have been in Jamaica and then back home in 1868.
Regards,
Daisy