wait wait Tamborine. Are you saying that the employer is responsible for your tax and national insurance contributions are paid to inland revenue?
In T's absence: yes! If an employer fails to deduct and pay to HMRC any tax and NIC due from an employee, that employer is held responsible and will have to pay ALL the missing contributions, plus interest and maybe a penalty as well. I wouldn't reccomend shero lets it ride, though. It might be alleged that he or she was colluding in the failure.
(Even if there's nothing to deduct, the paperwork should still be done; shero should be getting a payslip that shows the correct taxcode and a nil figure for deductions. )