Trade has always been central to the UK s prosperity. While it has always been recognised that air transport is crucial to these international linkages, there has been few attempts to quantify the value of air transport connectivity to the UK economy. Building on previous research by Oxford Economics, this paper explains how the value of connectivity can be measured by using an econometric model. We use the model to evaluate the connectivity benefits likely to be generated through building a new hub airport in the South East. It is part of a series of technical notes by Oxford Economics and Ramboll, prepared for Transport for London in support of Lot 4 of the Mayor s Aviation Work Programme the assessment of socio-economic effects. The Aviation Work Programme, in turn, has been conducted in order to develop a submission to the Airports Commission (or Davies Commission ) which has been charged with examining the need for additional UK airport capacity.