Hello Craig,
Is this your G. Uncle and his family?
1891 Scotland Census. Ladywell Cottage, Inverkeithing, Fife.
John Clarkson 32 Carter b Carmichael, Lanarkshire.
Elizabeth Clarkson 33 Wife b Dollar, Clackmannanshire.
Hugh P Clarkson 11 Son b Tillicoultry, Clackmannanshire.
James Clarkson 9 Son b Tillicoultry, Clackmannanshire.
William Clarkson 8 Son b Dollar, Clackmannanshire.
Elizabeth Clarkson 6 Dau b Culross, Perthshire.
Marion M Clarkson 3 Dau b Inverkeithing, Fife.
John Clarkson 2 Son b Inverkeithing, Fife.
Lewis Clarkson 4mon Son b Inverkeithing, Fife.
1901 Scotland Census. Drumcross Rd, Bathgate, West Lothian.
John Clarkson 40 Road Foreman b

Lanarkshire.
Elizabeth Clarkson 41 Wife b Dollar, Clackmannanshire.
Elizabeth Clarkson 16 Dau b Culross, Perthshire.
Mary Clarkson 14 Dau b Inverkeithing, Fife.
John Clarkson 12 Son b Inverkeithing, Fife.
Lewis Clarkson 10 Son b Inverkeithing, Fife.
Andrew Clarkson 8 Son b Inverkeithing, Fife.
Grace Clarkson 4 Dau b Edinburgh, Midlothian.
A possible for James?
1901 England Census. The Barracks, Caterham, Surrey.
James Clarkson 19 Soldier. Private, Grenadier Guards b Scotland.
In 1911, Lewis is based at same place but with The Scots Guards.
The family have moved around a bit & don't seem to have had any connection with Tillicoultry for years. I think the Bathgate/West Lothian War Memorials might be worth checking. I live near Inverkeithing in Fife so will pop along today to check there.
Good luck with your search.
Regards, Dod.