It appears no death certificate was lodged for him with what is today NSW Births Deaths Marriages.
Nor is there any record of an inquest.
Then last week I was contacted via email by a Mawbey in England who appears to be related to him.
The men in his family were printers at the London Times and John Evan Mawbey may have been their nephew and cousin.
This still needs to be confirmed.
This Mawbey in England also knew about a Henry Evan Mawbey, married 1874 at St Saviour, Southwark, London (Surrey), who was his great great uncle.
Coincidentally, this was the name of the father of the first Mawbey in Queensland, Henry Thomas Mawbey, who arrived in 1921 and became a politician and pineapple grower at Nambour.
It's so exciting when more pieces of the family history jigsaw come to light!
Update: February 2014
The father of Evan John Mawbey, born 1824, was Samuel Sampson Mawbey.
John Evan Mawbey who drowned was born c. 1817.
His father may have been a brother of Samuel Sampson Mawbey.
Henry Evan Mawbey, born 1851, was a son of Samuel William Mawbey, eldest son of Samuel Sampson Mawbey.
He married Mary Jane Joyce in 1874, and they were the parents the of Henry Thomas Mawbey, arrived Queensland, Australia, in 1921.