If you're heading for Britain's hills and mountains, there's simply no better companion than OS Maps – an app that puts all 607 Ordnance Survey maps directly into your pocket. And as if that isn't ...

‘I have a library of Ordnance Survey 1:25,000 maps that is augmented for each new trip. They are wondrous geographical and historical resources.’Photograph: Duncan Andison/Getty John Harris’s ...