Your man appears to have kept quite a low profile but if you have not already found it, you might be interested in this 1894 history of the regiment: http://archive.org/stream/historicalrecor00smytgoog#page/n10/mode/2up
This history does not seem to mention your man but does include quite a lot of detail on the campaigns in question, and on other events of note including cholera and the presentation of new colours to the regiment in 1840.
This last would definitely have involved your man if he was the colour sergeant at that time.
PS. As the regiment moved to Victoria in 1852, I had a quick look at Australian sources from this period and found several references to a John Filgate from 1844 on. If this is your man, you will find more at http://trove.nla.gov.au/