The contours were created by first digitising the 1903 survey by Murray & Pullar. I'm fortunate to own a copy, but it can be viewed freely online . Digitising, TIN interpolation, contour creation / smoothing were all performed in QGIS . 3D Spatial data is created by the Qgis2threejs plugin . Lake outlines are from the UK Lakes Portal , which contains OS data © Crown copyright and database right (2016).