I'm afraid you've lost me with that posting.
Are you saying that Dickson (Dixon) Hutchinson b 1795 married Mary Ann Todd in 1815 when she wasn't born until 1861? It really doesn't matter, because their daughter Mary Ann Hutchinson (b 1829) married XXXXX XXXXX and never left England. Mary Ann Todd was born in 1797.
Dixon Hutchinson and Mary Ann Todd did have a son John Fenwick Hutchinson (1822-1900) who married Jane Dorothy Wilkinson in 1844 in Sunderland. Their daughter Mary Ann was born in 1845. Here is the information you would need to order the birth record from the British GRO at http://www.gro.gov.uk/gro/content/
Name: HUTCHINSON, Mary Ann
Registration district: Sunderland
Year of registration: 1845
Quarter of registration: Oct-Nov-Dec
Mother's maiden name: Not available before 1911 Q3
Volume no: 24
Page no: 311
The family emigrated to Durban, SA in 1860. He was a joiner like his father and pursued that occupation in South Aftica.
There are no South African birth records online. South Africa makes very little available to anyone. Have you obtained their marriage license from the court house in Durban? Sometimes they will list the names of the parents' of bride and bridegroom.