I've read the topic from the start and I still don't really know what we are arguing about discussing, so to make it clear where I am I'll make the following points and Davey can then come back with his counter arguments.
1) The Earth on which we live is a globe, very nearly spherical in shape
2) The radius of the globe is approximately 6371 kilometres
3) A plumb line will always indicate the direction to the centre of the earth due to gravity
4) A level line is a line at 90 degrees to a plumb line at any point on the Earth and as a result, a level line follows the curvature of the Earth
5) Water at any point on the Earth will always settle level and therefore follow the curvature of the Earth (not taking into account wind, waves and tides)
6) Simple geometry allows calculation of other parameters, such as the distance to the horizon from a point on or above the Earth's surface
7) Jonathon Ross and Jo Brand are not funny
8) Ekona is a driving God
(Well maybe not the last one, but he knows what he's talking about when it comes to Porsches and tyres)