It is mid-afternoon and, in a field in rural Tanzania, a meeting about HIV services has turned into an impromptu karate lesson. Families laugh as people take turns to practise with Sister Kate. This is not how most nuns do community outreach. It’s more than 30 years since Kate Costigan – a motorbike-riding, karate black belt – left her home in Tipperary, Ireland. At 19, she entered the Missionary Sisters of Our Lady of Apostles, travelling first to Nigeria and later Tanzania. “My father wanted me to join a local order, not [be] a missionary that was going far away,” she remembers. Her family, not to mention her boyfriend at the time, were all a little surprised.