Recycling centre
"We take our responsibilities for protecting all information seriously and are extremely concerned as to how this single disk was not removed before the machine was taken out of use," he said.
"Recycling old computers was a conscious decision taken by the force as part of an overall cost cutting exercise and hard drives are always wiped clean but it appears that on this occasion the floppy disk has been overlooked."
Information stored on the disk also included firearms qualifications.
It was found by a man looking for spare computer parts at a recycling centre in Exeter, who alerted a national newspaper.
It follows the loss of details for millions of hospital patients, learner drivers and child benefit claimants.