It's Time to End the 'Data Is' vs 'Data Are' Debate (vice.com)
dmoberhaus writes: After receiving too many irate emails about using "data" in the singular, a reporter spoke to two lexicographers about how the language changes over time and why it's perfectly acceptable and perhaps even "standard" to use data as a singular noun, rather than a plural noun in an attempt to settle an old debate. Peter Sokolowski, a lexicographer for the Merriam-Webster Dictionary, told the reporter that data's transition between its historical roots and contemporary use is related to a lexical phenomenon called "semantic bleaching," where a word's original meaning is lost or diminished over time. An example of semantic bleaching include the contemporary use of the word "literally," whose Latin root, littera, means "letter." In the case of "data," it has transitioned from "things given" to mean something like "a collection of information in aggregate" when used in everyday speech.
Peter Sokolowski, a lexicographer for the Merriam-Webster Dictionary
His opinion on the English language doesn't mean anything as Merriam-Webster is an American dictionary. Get someone from Oxford and then I'll listen.