I'd encourage anyone to apply for the scholarship, as it's a very worthwhile experience regardless of whether you're successful or not. About 20 or so leading companies attend the interview day, and it's a really good opportunity to get to know a bit more about a career in engineering and how the industry works. Even if you aren't selected for interview I'd imagine the questions on the form are similar to what you'd be asked in an actual interview, so there's definately something to be taken from there.
Going back to universities, while I did meet a lot of Cambridge scholars, I don't think they're looking for academics alone, but motivated, ambitious students who might be leaders of the profession - at least that's the impression I got. Just as an example, Nottingham supposedly has the most quest scholars in it's department, and Cardiff / Manchester aren't worse.