Is this your man? (from Old Bailey site)
WILLIAM FORTUNE, Theft > theft from a specified place, 20th September 1847.
2091. WILLIAM FORTUNE was indicted for stealing I watch, value 30s.; and 9 sovereigns; the property of Donald Grant, in the dwelling-house of Robert Mitchell, and another: to which he pleaded GUILTY. Aged 17.— Transported for Seven Years.
Not sure if this is what you need, or if you already have it and unsure whether these have already been mentioned - quicker to type up than to look!! (Such laziness!) Also there is another W FORTUNE in WA so perhaps these are not him although his occupation is listed as 'saddler' except for the sickness record.
Western Australia, Australia, Convict Records, 1846-1930 for William Fortune
Convict Department Convict Lists, Memoranda, and Indexes (128/33 - 37)
William FORTUNE, C.P., charged with larceny at Perth,
committed for trial 20/11/1854,
trial 3/1/55, not guilty, discharged.
Twice in October 1856 a William FORTUNE, occupation: quarry, was listed as sick - bad eyes
ToL 29 March 1859
Judith