I'm open to correction on this, but I seem to remember that when prescription charges were first imposed, the prescription as a whole was subject to charge, whereas for many years the charge has been per item - £7.85 from this month). I worked out that, if I didn't receive free prescriptions, mine could cost around £100 per month, although of course there's the prescription pre-payment certificate which costs £104, a huge saving for a year's unlimited prescriptions, though a big one-off outlay for many people.