I interviewed with
Sidley Austin for their VS in 2018. Personally, it was the hardest interview i've ever had to do. This is because the two partners went through my CV in quite a lot of detail and would ask very technical questions. So the best advice I have is to avoid saying things you're not too sure on or can't recall too well! I was asked about the types of remuneration structures for fund managers and different structures of funds because I did an internship at a funds team a while back.
However, the interviewers were very friendly and it really is conversational, so just remember you can 'sort-of' control where the interview leads to depending on what you choose to say. I was also asked about what separates
Sidley Austin from other law firms and asked about what type of work they had done. So definitely prepare well! The Lawyer and other news sites, their website and the tables are all useful resources.