If one graduate at a developing country which lack highly ranked professors, how much weight should be expected to be given from Oxford University to recommendation letters for a Dphil? Do they weight it as much as letters of students with famous letters from famous professors? Are students with letters from famous professors preferred or they just access the content?
Well from my personal experience, I worked in an office where we were sending students to world top ten universities from Pakistan. We sent some to Stanford USA, and Oxford UK beside others. What I saw was that indeed weight is given if you are from a reputable university or not in a bad one at least. And that most of the weight is given to grades but most important is the research proposal that you write and your personal statement.
Also, a letter of recommendation not only states about you, but also the writing expresses the professor himself, how good he writes it.
Then if there is some research that has to be related to a developing country, then they will prefer you, especially if it's related to your country or like wise.
I myself got a scholarship in a good university under top 100, though lot of my friends with excellent grades didn't succeed. So keep trying is the key.