My experience (fresh grad position) :
1) walk in. fill up forms. (At this point I was shocked that the minimum to enter is a 2:2. That's REALLY low.)
2) given a case study and given about 30 mins + to prepare - (I refused to prepare because I read it and it was so open ended and almost too easy so I just chilled out). Tried to talk to the other candidate who walked out from the interview room but our conversation ended after he found out my uni. (??)
3) got called to interview room - walk in, smile, chit chat. 1 on 2. Let's go!
4) case study discussion - just breeze through like a boss! too easy. My advice is stay confident and try to control the discussion. Direct the discussion to areas which u are familiar with and give succinct pseudo-intelligent replies to questions which you. Have alot to talk about too. (you can prepare for this earlier during the preparation time, but honestly it's way more fun to do it spontaneously under pressure, if that was pressure)
5) competency skills questions - another easily prepared section. (eg. tell us of a time where u had to use innovative skills to solve a problem?)
At this point I was told it was finished. But I was not done and I asked "what about role playing? I heard there was a role playing part earlier. I'm excited for that. " *eyes gleaming because I was INDEED having so much fun in the interview I wanted to do the role playing too*
But alas the reply I got was "That won't be necessary. Only if we cant get info that we want from you in the earlier parts then we'll do the role play."
So I didnt get to do this but basically,
6) role playing (if you are asked to do this part means you didnt do well in the earlier parts and because PETRONAS gives ppl so many chances that you get a another chance - the role play chance)
7) say bye. smile. walk out of the London hotel. And knew pretty much for sure an offer is coming.
8) receive offer letter in writing 2 weeks later
9) contemplate whether to accept/reject the offer. (THIS IS THE HARDEST PART, I FEEL. Mostly because I guess I did not apply but was just called up for interview in the first place and the fact that I am not bonded to them)

So there, I didnt get a technical interview which is why I felt this interview was WAY too easy compared to BP. Maybe it's just formalities for the scholars/UTP students, I don't know. But yeah, have fun.
Unrelated link but it's something I was reading while composing this reply. A good take on our local education system in malaysia where critical thinking is so discouraged. My friends in UM are increasingly annoyed with how everyone is just suppose to shut up and accept and copy.
http://rickardoberg.wordpress.com/2012/02/...ry/#comment-113