Dr Hannah Fry is a mathematician from University College London. In her day job she uses mathematical models to study patterns in human behaviour, from riots and terrorism to trade and shopping. You'll also find her on BBC radio and television where she regularly presents science programmes, or on Youtube’s Numberphile channel. Dr Thomas Oléron Evans describes himself as a mathematician and a writer, though how others would describe him is anyone's guess. He used to be a secondary school teacher, but managed to escape and now has a research and lecturing job in London. While broadly agreeable, this does make life a little complicated, since he lives in Strasbourg, France.