Robert, Frederic, Eliza and Edward Smith had a brother named George, who after marrying in the 1850s left for Australia with his wife, Mary Victoria née Crump (daughter of Sleath John Crump). I have even got my hands on the shipping entry. They both arrived.
In Robert's will of 1917 there is no mention or bequest to any member of George's family that I am familiar with although there are plenty of names whose connections I have not made, although he never calls any of these spare persons 'nephew.' So either George had died or was persona non grata.
A family genealogist on Ancestry holds details for a Mary Victoria Crump and her sons, accounts for her whereabouts in the censuses but never mentions any further details on the sons, nor the husband, George. If this claimant be in possession of what is true then Mary V. Smith returned to England and is variously listed as a widow.
So what happened to George?