Here are permissions to marry I found two but yours is the second I am sure....
Search Criteria: Surname="agnew", Given Name="anne" Number of Search Results: 2 (1 Pages)
Family Name (1) Given Names (1) Ship or Free (1) Family Name (2) Given Names (2) Ship or Free (2) Date CON Ref RGD Ref AGNEW Anne Tasmania BELL Henry Anson 00 JUN 1847 CON52/2 p328 RGD37/6 : 1847/1134 AGNEW Anne Mexborough JONES Thomas David Clarke 00 OCT 1847 CON52/2 p247 RGD37/9 : 1850/754
That means Anne who came on "The Mexborough" got permission to marry Thomas Jones who came on the convict ship "The David Clarke"
There's another anne Agnew but she was free, but she married a convict so he had to get permission to marry.