The indent for the mary III states that Sarah (convict) had 3 sons and 2 daughters, with 1 son and 2 daughters accompanying her.
Thomas had been sentenced with Sarah and he came on the Mary Ann also arriving in 1835.
This left 1 son who was apparently too old (8 years or over) to accompany his mother.
It is possible that James was the name of the child left behind, it could also be the name of the son that came with his mother.
Andrew is stated to have been 57 when he died in 1879 giving a birth year C 1822 it is stated on Brian Lawsons site that he was born in Ireland and this was prior to the 1826 baptism.
I have found no other details of a "left behind" James but Andrew's guardian was William Quayle at Ballaugh.
Can you fit any more pieces to the puzzle?