I wonder how many private courier companies would be prepared to deliver a letter for me to, say the north of Scotland, for 42p.
I have sent and have had set to me quite a few parcels using the Royal Mail Special Delivery next day by 12 noon service as well as a lot of ordinary First Class post and they have all be delivered on time.
Royal Mail are far from perfect but I very much doubt that anyone else would offer the same service for the same or less. Parcels perhaps, but not individual letters.