There are copies in the borough archives of several letters of the same tenor issued during the 1420s. Such were evidently a means of identifying which townsmen were qualified, by citizenship or membership in a merchant gild, for the charter-granted exemption from tolls. However, it is not clear whether it was common to supply such letters to a town's merchants, or whether occasioned by special circumstances, such as in the case of John de Lyn, when fraudulent claims to exemption jeopardized the respect for rights of those who could legitimately claim it.

As a mediatized borough – one not directly under the king's lordship – Leicester's exemption from toll must have been limited for much of the later Middle Ages to the territories that were part of the honour of Leicester. Around the middle of the twelfth century the first so-styled earl of Leicester granted to his burgesses exemption from all customs that might be levied at points in the great forest encompassing the town, and forbade his foresters and other officers to stop the burgesses and their packhorses for such a reason (although a later confirmation suggests this may have been applicable only to timber obtained from the forest – on which see, Origin of some customs at Leicester). This was perhaps a confirmation of a privilege granted by the earl's father when lord of Leicester. Some years earlier, the king himself had granted the earl's men exemption from tolls solely at Oxford. But when King John in 1199 – pursuing a grant of privileges to the earl that included the right to collect toll, pontage, passage, pedage, stallage, tallage and various other revenues – granted the burgesses unhindered travel through the kingdom for purposes of trade, he added the reservation that they should pay legitimate tolls wherever they were due. Although in 1361 the burgesses gained control over tolls collected within Leicester, they still seem to have had no share in the kingdom-wide toll exemptions that the earl himself had received from the king.

When the town came directly under the king's lordship, under the Lancastrians, prospects must have seemed brighter. But it was not until 1416 that Henry V accorded the townsmen freedom from "toll, pontage, picage, murage, pavage, stallage, passage, lastage and carriage", even though his charter claimed they had been exempt from such since time immemorial. This charter helps explain the issuing of letters testimonial in the following decade, as both those qualified and unqualified sought to take advantage of the turn of events.