Yeah, found him
Thank you all so very much for the pointers and clues where to look. Duly noted that although the convict details are in alphabetical order of surname, once within a letter, the names are in no particular order. Took a while for that penny to drop.
Despite con(viction) records giving the wrong age at one point, (37 not 27) and his birth place as Emerton, Derbyshire (should be Hemmington, Nottinghamshire) the real give away was in the Indent(ity) details and the further notes that show his mother and father, and his siblings, all spot on with my records and his correct age. Another error on the 1841 Census for England also conspired to give a wrong transcribed age as 30 not 20 - they were rounded down and a check with the actual record gives his true age as 24. I've ordered his marriage certificate (surname in the GRO as Meryman) to an Ann(e) and a birth certificate for their son Joseph (b1840).
So Sam did not marry in VDL, Australia or NZ, but did his wife and child travel out, where did they live, did they have more children?? Can't see them on the census returns in England.
Once again many grateful thanks. This is now the second person we have found in our tree to have been forceably removed, hopefully he is the second to have found a new life and family down south.