Despite rape and other sexual assaults having low conviction rates, a London-based historian is optimistic this situation can be changed and offending reduced.

Prof Joanna Bourke, author of a book titled Rape, A History from 1860 to the Present (2007), said in Dunedin this week that rape and other sexual assaults were issues for men and society, not just for women.

Her optimism came partly from her perspective as an historian: ''I can see that things have changed and ... they can change again.'...