I did a technical exam first, and was then invited for a panel interview. This was all done through the local office, not with HQ. The interview lasted around one hour and covered both technical and behavioural questions. Both interviewers were members of the direct team I would be working with in the role. Informal but relatively technical. Do your research beforehand. Oxfam also has a distinct set of methodologies and approaches to development that should be well understood walking in. Particularly when working in-country, it is important to have a very firm grasp of the local context, partners, and communities. The main negative was how long the entire application process took: around 4 months between submitting and finally receiving an offer.