On the Halcrow side. PCC Wills on ancestry
Thomas Halcrow Mary's father wrote his will 2 May 1823 probated 9 June 1826.
States he is a provisioner for the Brig Rodney (looks like) of the Royal Hospital Greenwich Kent.
To George Mainland son of George and Mary Mainland, granddaughter Mary Ann daughter of Jane Linah by a previous husband*, Mary Clouston? my sister daughter Mary**, my daughter Mary Mainland widow of the late George Mainland deceased, daughter Jane Linah wife of John Linah.
Probate by executrix Jane Linah and Mary Foster formerly Mainland wife of John Edward Foster.
* this is a fib Jane Halcrow spinster married John Linah 7 August 1814 St George In the East. witness Thomas Halcrow and J ?arsall
** there are no commas so is Mary Clouston? the sister or his sisters daughter.
The Brig Rodney existed there is an article about it and it was stationed at Greenwich.
ADDED possible burial for Thomas Halcrow 10 September 1825 aged 67 at St George in the East he was of St John Wapping.
It will be worth your while to contact the Maritime Museum re details of the Brig Luna that George Mainland took to Montreal 1820 plus his career/other ships he sailed on.
John Edward Foster was also a Mariner per marriage of daughter Maria Jane 1839.
There is also the East London Family History Society they encompass the docklands area.