Thank-you.
The Ogilby Trust website refers back to the Green Jackets archive, so this appears to be an example of the Circumlocution Office.
Thank-you for your links to the other sites, but unfortunately they are not relevant to records for a soldier in 1815.
I do not want to pay for research. Although visiting the archive will cost me more, I prefer to do my own research. The archive certainly has the muster rolls. I've seen several references to them, and examples of other soldier's service being traced through them -- Sergeant Himbury's for instance.
I will write to the archivist in the hope of getting some response.