Roy previously mentioned the rate increase to come on April 6. I just posted my usual summary to my web site.
While writing the post, I ran some quick calculations on the increases. They are whoppers! Every basic rate increases by more than 10%, except the first-class letter rate which, going from 36p to 39p, is only 8.3%. The increase for the lowest weight large letters is more than double that!
Also, Douglas Myall reminded me that the 54p Machin issued in 2007 is still enjoying a relaxing vacation at Tallents House (where I suspect it is quite a bit less than 20 degrees). Its vacation will end in April when it is redistributed throughout the UK to handle worldwide surface mail duties. So there will not be a brand new Machin for that value, though there probably will be a new cylinder.