Thanks to Denis Stevens, I can show you the phosphor band layout of the 2010 Machin Exhibition sheet.
Glen actually gave me permission a few years back to use some of his images which are protected by copyright on my web site, in return for a permanent link to his site. I am hoping this permission still stands otherwise I am in trouble (again).
I recommend a visit to Denis,s site, his entries are cross referenced with Deegam numbers, Stanley Gibbons , Stoneham and Concise. He also has some useful information on Machins and GB stamps in general, not to mention the images which must have taken a lot of time to prepare and list.
I was pleasantly surprised to see actual phosphor bands on this sheet, rather than Optical Free Phosphor Paper which was used on the previous Matthews mini sheet.
A slight phosphor shift in any direction should produce some very nice errors (let me know if you find any)