Today, Paul from Edazzle has replied saying:
It's because Amazon doesn't actually remove any items from a wishlist, even when purchased, they just allow you to filter them based on whether how many are desired and how many have been purchased.
What I've done is instead of showing a price and buy button I've put in purchased instead. Take a look at your AmazonBox and let me know what you think. I don't really want to take the items out of the AmazonBox because only ten items are returned for each page call to Amazon - so if someone wanted to display 10 books but 9 had been purchased then they would only see 1 book.
On Amazon.co.uk the wishlist is filtered between purchased and unpurchased - to remove them from the Wishlist you need to actually delete them yourself - then they will disappear from AmazonBox as well.
Hope this helps.
In other words, he has explained why the problem arose and revised the product to help me in a single day! This has profound implications for doing business in the 21st Century ..... blah, blah, blah.
If the court will be upstanding I will deliver my verdict: Paul of Edazzle is a groove and a gas - everyone should send him money and other fine things.