Proj4 is an excellent little utility for coordinate conversion allowing the transformation of map coordinates from a slew of map projection systems.
This tool simplifies coordinate transformation and is especially suited in automating the coordinate transformation for any area. By considering the Kenyan case, two systems have been dominant in their application. These are the Cassini-Soldner and the Universal Transverse Mercator (UTM) coordinate systems. By analyses of the UTM system used in Kenya (zones 36 & 37 both North and South) there is perfect agreement with Survey of Kenya computations, i.e. transformation from Geographic coordinates to UTM coordinates and vice versa.
Unfortunately, direct Proj4 computations of the Cassini Soldner are not consistent with the computations from Survey of Kenya (SoK). Geographic to Cassini-Soldner transformation indicate inconsistencies that aren’t easy to model as yet, though there are counter strategies to support that. A work around is the use of the famous Affine Transformation parameters that are currently used as a nation. At some point though it is expected that the Proj4 tool will be used instead supporting the C-S <=> geographic <=> UTM approach giving exact values. This will address the small discrepancies that arise from the application of transformation parameters.