Who pays for prescriptions contained by the UK?

I was given a prescription today for oral contraception. When i took it to the chemists I be told I did not have to retribution. I am 27 years old and contained by full time employment so why was it free?Who pays for prescriptions contained by the UK?
In the UK adjectives prescriptions for the oral contraceptive are free. However if you needed say..an antibiotic etc - you would hold to pay.
Generally you grasp free prescriptions if you are: Under 18 in full time coaching, over 60, unemployed and recieve jobseekers allowance, hold a medical exemption, a maternity exemption, procure income support etc..
NHS pay for yoyr prescripition on clinic