Southwell Fibresand, for me, is easily the most interesting track in the country to study (followed by Newcastle and Wolverhampton Tapeta). Speed figures gained at Southwell are by far the best way of backing winners (long term) there and it is unusual for a meeting to pass without a couple of winners being highlighted on that basis. I ignore speed figures from other tracks there, and Patternform is the tool I use for isolating them.
I think you are using ‘Inform’ ratings Sunchu. Are you able to see which Course each figure comes from, and are you therefore able to isolate them? If so it will be interesting to see if they do better than the ones I use, which effectively, are an amended version of the Racing Post ‘Topspeed’ figures. Unfortunately, there has only been one meeting here since the Spring due to track maintenance so we will have little or no recent data (although I can go back as far as I wish using Patternform).
I must admit, I find it difficult to understand why providers of speed figures on the all weather, do not separate the three types of surface. Even then, Polytrack at Chelmsford is not the same as at Kempton or Lingfield.