Any ideas welcome missing man in 1851 census

[troods]

Hi Everyone

I would love to hear any ideas or hints as to where to look next for my missing ancestor.

I can't find my James Shipwash Hall in the 1851 where I thought he would be and thats in Kent. He was born in 1822 in Kent and his father and stepmother and younger siblings are in Kent but not him.
He is defintetely still in England because he left in 1852 to come to Australia arriving in Oz later that same year. I think he came out to Australia with a wife as well.
So I have abit of a dilemma. Where do I look for him.

I came across an entry on Free bmd for a marriage of a James Hall to  a Mary Holmes in St Georges Hanover square in  Dec 1850. This matches up with the name of his first wife who died in Oz just after arriving there.

I hope I am not confusing anyone too much, but my James Shipwash Hall seems to a very elusive man in England prior to coming out to Oz.

Hoping some one can help me

Regards
Troods