Talks: Professor Gerry Gilmore (Cambridge University)Gaia: the 6-D Milky Way map is coming to you Dr Simon Mitton (St Edmund's College Cambridge)Georges Lemaître: Life, Science and Legacy RAS 2016 HAROLD JEFFREYS LECTUREDr Jenny Collier (Imperial College)Making Britain: evidence for catastrophic flooding in the English Channel It has been previously suggested that the separation of Britain from mainland Europe in the late Quaternary was a consequence of a catastrophic flood caused by a spillover of a proglacial lake that occupied the present-day southern North Sea basin during the Elsterian glaciation. Such an event would have significant palaeogeographic, biological and archaeological implications, but it remains controversial. Ten years ago we discovered a drainage system carved into the floor of the English Channel that is consistent with the catastrophic flood model. In this talk I will present a new compilation of geophysical data that we have used to analyse key landform features both within the downstream region and at the proposed breach point at the Straits of Dover. Our observations support the hypothesis that the landforms were initially carved by high-water volume flows via a unique catastrophic drainage of a pro-glacial lake in the southern North Sea at the Dover Strait rather than by fluvial erosion throughout the Pleistocene. The system also shows evidence for modification by a second flood that may have been a consequence of spillover of younger ice-marginal lake systems to the east, either in the North Sea basin or mainland Europe.