Fix to error in 1.2 spotted by Carolin Stang (as listed in issues) - 1.1

Fix to error in 1.2 spotted by Carolin Stang (as listed in issues) - 1.1 and 1.2 producing different results. This was due to a change in the SpatialGrid method, and as such this has been returned to the method used in 1.1. 1.2 now produces results that equal that in 1.1. However the 2D padding has been reintroduced into 1.2, as it was in 1.1. This obviously needs more examination, and will be addressed in due course