St John's College is a constituent college of the University of Oxford. It was founded in 1555 by the merchant Sir Thomas White, intended to provide a source of educated Roman Catholic clerics to support the Counter-Reformation under Queen Mary. St John's is the wealthiest college in Oxford, with a financial endowment of £442.2 million as of 2015, largely due to nineteenth century suburban development of land in the city of Oxford of which it is the ground landlord.