NHS Wastage:

I had to call NHS @ Reading yesterday to change X Ray appt. at our local hospital;
the new date was quickly sorted and they said they'd confirm by post.
Fair enough, but why the need to use 1st class post for an appointment 4 weeks away.

The difference for franked mail (2nd versus 1st) is about 14p, so the savings could help the NHS's
known budget crisis.

Save a lot more if they confirmed by email or sms.

There are many different commercial contract rates, it's a competitive market. For instance, dependent on volume, agreeing to pre sort, have collected from one location etc. All things which are straightforward for bulk users with access to central printing and dispatch capability, the price may well be far lower than you think. The first and second class labels on these envelopes are really only internal sorting symbols.