I applied online. I interviewed at IBM (London, England) in Aug 2018
Interview
Lots of online numerical testing, including IPAT which I personally found very stressful however I am not the most mathematically inclined. Do online practices as they help. After all the online tests I was invited to an assessment centre which was very relaxed and not what it is made out to be online. It is very laidback and friendly, even the presentation/interview. Be confident and be yourself.