So Elizabeth's youngest child as per 1851 census was born 1843, 1844 or 1845 (aged 6)... and she is recorded there as a widow aged 48. Have you sought (just in case not Baptists) any baptism records for the younger children to check if the clergy noted any possible margin notes re any punative father ...
Not every person who arrived in Van Diemens Land was a person under the sentence of a civil court ... there were the soldiers who came as garrison forces, the administrative staff, the clergy, the surveyors, the settlers, many people came to VDL by sea who were not convicts.
If a female with children to support is found recorded as a Widow on the 1851 census I can appreciate that the word 'widow' may have a broader meaning than a person whose marriage has ended with the death of her lawful husband. So it may be possible that the marriage had ended by a sentence of transportation beyond the seas, or he may well have simply moved on, to a different town/county or migrated to a different country ... 1851 ... Gold Fever in California commenced in January 1848 ... Non conformists supported the Wakefield Emigration schemes ... New Zealand in the 1840s, or the Colony of South Australia .... or just about anywhere within the realm of the Empire...
JM
