Applied online, got an invite for online assessments after a few days and within a few hours got a notification that I passed that stage. I had a very quick experience with Rolls Royce, within a few days they had checked my resume and motivation and the online status changed to 'to be invited'. It did take an additional 1,5 week for me to actually receive an invite for the assessment centre in Derby, UK. They paid for my flight & necessary accommodation to attend the assessment centre.
The assessment centre consisted of a brief presentation about yourself followed by a compentency interview. Then we had a technical interview, which was quite easy in my opinion as the interviewer tried to only ask questions in the fields I was comfortable in. Lastly there was a group exercize, it was fun but I struggled a little with the strong British accents of the fellow interviewees, whom, due to the time pressure of the exercise, started to talk very fast.