Mathematics has a long history. Oxford Mathematics is younger, if 800 can be described as young. For an account of those eight centuries, see Oxford Figures: 800 Years of the Mathematical Sciences, edited by John Fauvel, Raymond Flood and Robin Wilson, and published by Oxford University Press (second edition, published in September 2013).
For a brief (and not up-to-date) account, see the text of a lecture by the late I. W. Busbridge, who was a fellow of St Hugh's College from 1945 to 1970. It is reproduced here without revision. Much has happened in Oxford since then, but her account is still of great interest.
We have also produced a series of posters for display on the mezzanine floor of our building featuring Oxford Mathematicians of the last 800 years.
The Mathematical Institute also has a collection of 19th century plaster and metal/string models of mathematical surfaces, quite likely purchased by JJ Sylvester. Here are full descriptions and the mathematics that underlies them.