Valda, I tried many years back using a researcher.... managed to get the full military history of his son John (12th Royal Lancers, 1814-1835) - have heaps of info even including newspaper articles etc. on him - interesting careers after the Army hence the references I managed to locate.
Alas the researcher couldn't find a thing on Lewis ANGUS.
A couple of certificates circa 1852'ish (wifes death and another one) mentions him as having been a Military Officer.
Had discounted that for a while once I found him recorded as a clerk in HM Tower of London 1811... then the new info re death at Woolwich and that there was the Military College for the Artillery there has me re-thining along those lines again.
I now have the marriage of Helen ANGUS and John GRIEVE - on the Sabbath 7/7/1776 which pre-dates where I am at presently. Coincidence that my Lewis marr. 7/7/1799 - must be something about 7th July

If all else fails I hope to retire in about 5 yrs so a good excuse for a holiday in the UK !