What they reveal is the prime minister, and his wife Samantha, love nothing more than pointing at fish. If they're being photographed at the same time, all the better.
The curious aspect of these pictures is that last year, just 100 miles away in Aljezur, the Camerons visited another fish market, and, to their apparent delight, couldn't stop themselves from pointing at fish.
The even more curious is that, even for a man who gets photographed a lot, Mr Cameron has appeared in a lot of fishy photos.
This was in 2011.
But 2010 was the real boom year.
Basically, expect to see the hashtag #longtermeconomicfish making its debut on the PM's Twitter profile any time soon.