To whoever it was who asked the question of getting a job with a third - yeh of course you can, especially if you're from Cambridge. Often it's the potential and quality of the graduate that counts, rather than how good you can at the subject anyway (depends on the job, of course.)
Anyway, yeh, my friend's dad got a third from Cambridge and he's an engineer now - think he built some large bridge somewhere too. He broke with the stress, basically why he got a third.