Orton Horton Family of Kalbar Queensland Australia Elliott Mckenna

I am relatively new to searching for my ancestors, however I can always do with some help.

I have come up against a couple of brick walls at present

In researching the HORTON family who settled in Kalbar, Queensland I would like to know when they changed their name from ORTON to HORTON. In the 1851 and 1861 English Census and in the shipping record for the "Light Brigade", on which they travelled to Australia ( 1871) they are recorded as ORTON. In later information, (cemetery records, headstones, death certificates etc ) they use the spelling HORTON.

I am also looking for the parents of John ELLIOTT 1810-1885 born Monaghan, Ireland and his wife Mary McKENNA