Hello Leanne

Did you get Thomas's details from the records of the ship "Star of the East" or from the list of Manx people who immigrated to Australia? Thomas was aged 29 when he arrived in Melbourne.
Thomas's DC in Victoria 1882 online looks a little confusing.
Marriage of William and Catherine:
William Gawne of this Parish of Rushen and Catherine Carran of the Parish of Patrick 12/2/1824. William and Catherine bothed signed the document , so both could read and write. Witnesses were Robert Carran and Thomas Gawne.
Thomas was christened 9/2/1825 Rushen to William Gawne and Catherine Karran. It staes he was ch privately 9/2/1825 and received publicky ( As spelt) 24/4/1825. Frances may be able to explain what that means.
1851 Census Rushen
William Gawne 55 a Mason
Catherine 48
Thomas 25
Catherine 24
Margaret 17
Elizabeth 15
William 12
Maria 11
John 9
Robert 6

All shown born Rushen except Catherine Snr born Douglas.

Also found births of Henry 5/4/1829 and Jane 31/7/1831.

Williams age 55 and 45 in 1841 indicates born c 1896 , but I cannot find one born in Rushen. Most likely one born Ballaugh 20/3/1896 to John G and Margaret Mylrey.

Catherine looks like Catherine Carran ch 13/2/1803 in St Georges Douglas to John C and Elizabeth Kenney.

There were three other Manx people on the "Star of the East" into Melbourne:
Samuel Leece
John Quayle
William Quayle.

There are a few William listings on the LDS IGI by user nominated trees where wrong spouses have been allocated.

David Dwyer