Got interviewed 2 times by National Grid for the same position (but different vacancies). Both interview have the same process in general as follows. One time interview only (no follow-up interviews), consists of 3 sections: Icebreaking (background, motivation, etc); technical and case study, and the competency-based sections. 1.5 hours interview, 15 mins for both ice breaking and the competency based, and 1 hour for technical and case study. The interview is not that difficult as long as you know your stuff. But personally, I don't think a fresher stand a chance for the technical interview part (unless you are insanely good).

Simple recorded interview and then assesment centre which was well organised! Mixture of technical and non technical questions, entire day long. Non biased with a different interviewer for each stage