Australia.
The earliest reference I can find in Australia is in the Census of NSW 1828 held at Myddleton House, London:
Blackstone, W. Mariner on the Phoenix Hulk, Sydney B1331.
Beyond this reference, there are three families in Australia that I am aware of who's lineage I can trace:
That of Thomas Bradley Blackiston, christened at Rochester in 1766, son of Christopher Blakestone & Lydia (nee Bradley). Thomas was an Ordinance Surgeon who died in 1813. His father Christopher was also a surgeon. His origins are in Beverley, ERY. Traceable to Thomas Blayston of South Dalton (d.1543). His brother Lt. William Blackiston (1771-1848) is the founder of Blackiston dynasty in and around Sussex.
Maria Susannah Kemp (nee Blackiston) dau. of Thomas Bradley Blackiston
printed with kind permission of Sephi Kemp
Two brothers, Edward & George Blakiston, who both left for Australia circa 1840. Edward died in Geelong in 1903. George taught in Beverley, Australia. They can both be traced to an Edward Blakiston & Mary (nee Tinkler) at Barnard Castle. Possibly this Edward was the son of a John Blakiston & Isabel (nee Cass). This family has been documented by William Collins Blakiston in 1908 (54). Somehow this family is connected to either the Norton family or Seaton family, of Durham, or both. Gene studies would be useful here.

published with permission of Dianne Davis.
I know of a further family in Australia today who stem from a William Blakiston of Cockerton (abt 1801-1862). My suspicions are that William was the son of a George Blakiston at Cockerton. This George being a son of Edward Blakiston & Mary (nee Tinkler). Hence, connected with family 2) above.
The elderly Gentleman is probably William Collins Blakiston, of Hythe, Kent, aged about 87 in 1908. In that year his nephew Jonas came on a visit from Australia. Possibly Jonas on the right. (photo. by permission of Peter Blakiston).
Is this William Collins Blakiston with his 2nd wife Mary (bn.1811) & 3 daughters; Maria (64), Clara (62) & Alice(55)? Possibly also Jonas' son James (36), his wife Sarah & their two sons.