Old £1 Coins Edge Inscription Errors

On British £1 coins, the edge inscription is stamped as an additional stage after the coin itself is struck; the coin goes through various buckets and rollers in between those two processes, meaning that the orientation of the edge inscription is random; half of them are "up", the other half "down". The only "edge error" on the old pound coins would be if the edge inscription is missing entirely. On the proof versions of these coins made for collectors, the edge lettering was included in the collar die and applied at the same time as the coin was struck, so there is only one "normal" orientation for those, but you're only likely to find proof pound coins in proof sets.

You can very often find British pound coins that appear to be "mules" - the date on the obverse is not the correct date for that reverse design. Such coins are not in fact mules or errors, but actually counterfeits; counterfeiting of the old pound coins was rife, and the counterfeiters rarely bothered to get the obverses and reverses matched up properly. This prevalence of counterfeit coins is of course why they switched to the new pound coins in 2017, with more security features.

The edge inscription is applied to the blank planchets before striking. The reeding is engraved in the collar and is superimposed on the edge inscription during striking of the coin. I assume the same procedure is used in striking proof coins but perhaps the proof blanks are inserted and oriented manually between the dies so these may have the inscription in one direction. Although I doubt the orientation of the blanks will be done.