First interview is initially to see if you are a fit.
Questions at this stage are straight forward and akin to an informal chat about your experience, why you want to work there etc. It is impact investing so make sure you research the organisation and that you understand their goal/focus.
Second interview is based on a case study (which you must submit before the interview) and then attend a panel interview (so meeting more people within the organisation) to answer questions. Some technical questions will be asked and also some competency questions based on the spec. Nothing too tricky.
I must highlight that the actual people within the relevant teams are very friendly, professional and knowledgeable. They are not the issue.
The terrible part of the experience - the HR side of things. you will have to chase for anything to be done/to be told anything, pro-actively updating candidates doesnt seem to be a thing. The co-ordinator is very unhelpful, slow to get in touch and arrange anything they have been advised internally to do, leave candidates hanging yet quite rude and snappy when candidates politely reach out for an update - bear in mind you are literally only reaching out in line with the timeframe you were given in the conversation by the actual interviewers yet you get your head bitten off!
You can apply maximum effort, invest a lot of time to engage in/accommodate their process just for everything to be slow and drawn out by HR and no constructive feedback in the end.
Very unfortunate process.