Historically it has been identified that the Davis name originates from Wales (for more information check out the Davis Name Meaning).

Walker is an English and German surname derived from either a fuller, from the Middle High German walker,[2] meaning "a fuller of cloth", or an officer whose duty consisted of walking or inspecting a certain part of a forest. The name is common in both England and Scotland

Research has identified that the family line that is recorded as Davis is actually Walker, with the current known progenitor of our line being Thomas Walker aka William James Walker aka Thomas Davis, who is first found in Australia Australian records in Victoria in the 1850s. It is believed that Thomas was born in Australia around 1820. 

The Davis ancestry goes back 6 generations and biographies exist for some members as indicated by links

• Thomas Walker aka Thomas Davis abt 1820 - 1905 married Jane Bygrave 
  
  • Louisa Jane Davis 1865 - 1942 married Patrick McDermott
    • Emily Louisa McDermott married Sydney Walter Jessop
      • Esmond Early Jessop married Mary Agnes Darrough
        • My Mother

Finding Thomas has become such an obsession that I have begun an exercise to identified EVERY (or as close as I can get to it) DAVIS in NSW pre 1840. I am desperately hoping this will turn up my Thomas. As I complete my ship by ship journey, I will be updating my Davis's in Colonial NSW pageDavis is a patronymic surname originating in Wales that means 'son of St. David '.[2].  It is derived from patrynomic form of the male given name David, itself coming from the Hebrew name Dodaveha meaning 'beloved of Jehovah'   It is the 45th most common surname in England and 68th most common in Wales. It is often interchange able with Davey, Davies, Devis, Davie, Dafis, Dafys proven to be a significant challenge. Thanks to Jen Christianson for identifying a potential marriage record for Jane under the name McDowell in Victoria in 1858.