The Testament of William Thorpe was published around 1530 as an appendix to Thorpe's longer Examination. Many scholars, however, doubt the attribution of the Testament to Thorpe because, whereas the Examination is dated 1406, the Testament is dated 1460. One scholar has recently argued that the 1460 date be amended to 1409, based on the observation that when these numbers are expressed as Roman numerals, MCCCCLX and MCCCCIX, it becomes easy to see how the dates might have become confused through scribal error.
Few writers in fifteenth-century England marked dates in their works using only Roman numerals would most support the scholar's hypothesis concerning the date of the Testament.