London Gazette On line

Go to the Gazettes Online page www.london-gazette.co.uk
near the bottom right hand side of the page it says in a Blue Bubble “Search
the Archives” and click on this link. 
Go to the bottom of this page and where it says Words put in a word, I
usually look CUMPSTON people and in the spaces above put in dates.   I usually search a decade at a time e.g. 1 January 1790 to 31 December 1800 then you will get a page of results with a link to each page

One I found there was under the heading of the West Riding of Yorkshire Artilliary Volunteer Corps. First Lieutenant Thomas Bowser Cumpston resigns his Commission. Dated 1st February, 1873.  You can read more about him on my website at http://www.cumpston.org.uk/#/thomas-b-cumpston-leeds/4533331988