Terrafire , I've got some UMS conversion tables you might find interesting for Edexcel Maths which give the exact conversions between raw and UMS.
Your program works pretty well from what I can see but some raw marks don't seem to be mapped into UMS marks.I got 85/100 for Core 4 last year for example , which I know from Edexcel online to be 62/75 .The lower E grade boundary was 29 on that paper and the A boundary was 58.It claimed that I'd have had to get 65/75 for 85 UMS .For 84 points , the program says I needs 64/75 , 83 - 62/75 , 82 - 61/75 , 81 - 59/75 (what happened to 60?) and 80 correctly as 58/75.