Someone that leases a vehicle for their own use, this means that it therefore can't be used for business purposes and only a single person is able to drive the vehicle.

Personal use of an organisation’s vehicle includes use that is not business-related such as commuting to the driver’s workplace which is generally a taxable benefit in kind. The rules on private use s [..]

Personal use means activity that is conducted for purposes other than accomplishing official or otherwise authorized activity. Executive Branch employees are specifically prohibited from using governm [..]