The longest review posted on Amazon UK is another American review, appearing here because nobody has posted a UK review. It also has a 12-word caption, but contains just 5,137 words in the body of the review, making a total of 5,149 words.
The Haunted Universe
I don't think reiews of such a length would get past the UK filters. What is the longest review actually posted on Amazon UK rather than appearing here but marked "Published in U.S." ?
I've written one with 1,370 words in the body plus an 11 word caption for a total of 1,381 words, but surely somebody has seen a longer one?