The peculiarities of British postage stamps

A few years ago, the Royal Mail changed the way it handles postage stamps for standard letters. Previously, if the rate for a first class letter was 27 pence, then the stamp you bought for the letter was one with "27p" printed on it. If the postage rate later went up to 28p, then you would need to buy a 1p stamp as well for the letter to be send first class. However, with the new system, a first class stamp simply had "1st" printed on it, and it was valid to be used for first class mail forever. If the postage rate went up, the stamp was still valid. The post office would continue selling the same stamps, but would just start charging more for them. This didn't cause problems, because if people bought stamps earlier the post office had their money earlier, and in fact if people did this a lot then they would probably be funding the post office's working capital requirement at a cheaper rate than a bank would do. The Royal Mail would also save money by not having to issue new stamps with the new values. However, the one disadvantage of this is that people would probably buy lots of stamps a few days before a postage rate increase, and therefore it would take a little while for the postage rate increase to take effect.

These special stamps come in three varieties: "1st" for first class letters, "2nd" for second class letters, and "E" for letters to most European countries. If you are sending mail of any kind other than standard size letters to these places, you normally use stamps with numerical values on them to make up the correct amount of postage. However, it is possible to use the "1st", "2nd", and "E" stamps to make up part of the postage of another rate. The "1st" stamp is simply equivalent to a numerical stamp of whatever is the value of the present first class postal rate.

Yesterday, I wanted to send a package to a friend of mine in the United States. The postage turned out to be 2 pounds exactly. Fine, but I discovered I was not carrying enough change. Therefore, as I had some books of first and second class stamps in my wallet, I decided to use those. As 1st class postage was 27p and 2nd class was 19p, I was able to quickly figure out that six 1st class stamps and 2 2nd class stamps was equivalent to 2 pounds. I put the stamps on the package, but I did not send it as I didn't have my friend's address with me. I brought the package home, and forgot about it. Thus I still have the package.

Today, however, domestic postage rates went up, but most international rates did not. The rate applying to my package stayed the same, but 1st class postage went up from 27p to 28p, and 2nd class from 19p to 20p. Therefore, the stamps I had put on the package were now equivalent to numerical stamps worth 2.08 pounds. Even though the postage was correct yesterday and the stamps on the package are exactly the same as they were yesterday, there is now too much postage on the package. Today, I could use five 1st class stamps and three 2nd class.

I could carefully peel off one of the 1st class stamps and replace it with a 2nd class stamp, but somehow I don't think I will bother.