It happened with the Diamond Jubilee miniature sheet in 2012 and I thought it might happen with the Penny Black (and might still happen with Long To Reign Over Us.)
This first day cover has a full set of stamps - indeed all the elements of the miniature sheet - but in the wrong order.
This cover has been cut from a Press Sheet - the person who produced it has carefully cut across the middle of two of the miniature sheet impressions and divided the stamps, providing a 'miniature sheet' which has been miscut, but it is not a miscut in the accepted sense of the words.
A miscut - as in booklets from the 1980s - results from an incorrect machine setting which divides the stamps which are in two vertical columns or horizontal rows in the centre position instead of the correct positions. Or the Sheep Post and Go Faststamps which resulted in various different Sheep appearing at the top of the strip in presentation packs.
This is a deliberate novelty cut from a press sheet which results in spare stamps at the top and bottom of the sheet, stamps which can only sensibly be sold as individual stamps or used as postage.
I expected to see some of these on eBay as we did the Diamond Jubilee MS fdcs. I haven't seen them on eBay but spotted this one at a local fair. The dealer acknowledged it for what it was, and said that he hadn't produced it.
Buy one if you like it, as a novelty, but not as a print-factory-produced miscut.
GREAT BRITAIN ~ 2015 London Autumn Stampex Cover - British 2015 Autumn Stampex cover, posted on September 16, 2015 from London to Taipei with arrival postmarked on October 5, 2015.