Hertford knows that only the real Edward will know where the Great Seal is because Henry gave it to Edward to hide before he supposedly went mad. The fact that Tom is starting to remember frivolous things like how to dine in public but not a very important thing like where he hid the seal doesn’t seem to concern Hertford, though. This suggests that Hertford, despite his suspicions, still prefers to think that the King of England is really mad rather than believe that Tom’s story about being a beggar was true. Again, this demonstrates the willingness of people to cling to what they see rather than to believe what they intuit to be true.