This really annoys me on ebay. You are quite correct in stating that the edge inscription is applied to the blanks before the coins are struck, and the blanks are then placed into a hopper that feeds them between the dies. This applies to most of the 1983-2016 £1 coins and most £2 coins since 1997, apart from the 'Bridges' series of £1 coins and the London Underground £2 coins which had symbols on the edge.
Unfortunately some people seem to have got it into their heads that the edge inscription should always be legible when the Queen's head is uppermost, and that any coin with the writing the other way up (as you say, 50% of the production) is an error... The story got picked up by a clueless reporter on one of the UK's tabloid papers, and, despite many attempts to debunk it, it just continues to run and run...
Unfortunately some people seem to have got it into their heads that the edge inscription should always be legible when the Queen's head is uppermost, and that any coin with the writing the other way up (as you say, 50% of the production) is an error... The story got picked up by a clueless reporter on one of the UK's tabloid papers, and, despite many attempts to debunk it, it just continues to run and run...



















