This cover was discovered in the first half of  the last century in  the Fortescue / Porters   correspondence.    All   four covers of the Fortescue/Porters  Correspondence including   this one are illustrated  in The Postage Stamps of Great Britain, Volume II  by Wiggins and Gardner - Hill, Photo Plate1(after page 16). The silhouette shows an example of the correct vertical and horizontal serpentine  configuration of the Treasury  Roulette which should  have approximately four “waves” to the length of the stamp.

From London with  Inland Office  No. 12 Cancellation  to  Winslade,  Exeter, 7  January  1854,  with  “TOO  LATE  G. P. O.” Cancellation.    Ex Bertram McGowan Collection

The “Treasury” or “Gladstone”  Roulette  received its name as an example was found bearing the name  of Gladstone  when he  was Chancellor of the  Exchequer of the Treasury (28 Dec 1852 - 22 Feb 1855). The Treasury Roulette has been found on plates ranging from Plates 155 to 177.