The process is very simple, I would look at it as if it was a video game, you have to do the same thing at all levels, only a little more difficult every time.
1-Screen interview: phone
2-First interview with Barcelona Recruiter, in my case, Roberta (super nice and very helpful, she actually motivated me to stay in the process and move forward!!): Conference call with a video call.
3-Second interview with UK HR: Conference call
4-Third interview F2F with HR, Sales manager and VP sales
1: They only want to get a grasp of who you are, what you've done and what motivates you.
2: Role-play and questions they really prepare you for, you will get all of the information by email and that's all you need to read really in order to be successful.
3: The exact same interview, only a different role play. Prepare the Gartner traits with different examples
4: Same as number 3, only face to face.
The most important thing is to apply all the feedback you're given into the next stage. Before every interview, the HR that is managing your process will prepare you for the next stage, take advantage to ask for feedback and improve your pitch.
Maybe I accepted my offer too quickly, you may want to negotiate your salary before you do so (still was a good one).
Overall it was a very good experience, you only need to be open to the feedback, apply it and be ready to learn!!