The holes I noted at Rye that featured these sleeper walls were mostly par threes.
2nd par 3 - left of the green between two bunkers
3rd par 4 - short right of green at top of a grassy hollow
7th par 3 - short of the green, a pair of walls between the putting surface and a bunker
14th par 3 - right of the green
Least these are the ones I noted when I was there in 1995.
Marc, I'm not sure if there is much physical retaining of soil done by these walls as they are rather low, but Craig thinks the Littlestone one was put there to help hold up the right side of the green. Perhaps this is part of their reasoning at Deal but it doesn't look to me like they are needed for that reason at Rye. Could be wrong.
Thanks Andy for the photo of the wall at Littlestone - this is quite similar to the one at the right of the green at Rye's 14th. Craig, interesting you mention that this was put there fairly recently, so they must have copied the ones at Rye down the road.
Tom, had a sneaking suspicion that you liked these, as I read your write up of Rye in the Gourmet's Choice section of the Guide. Even though you didn't mention them specifically, I knew you held their par 3s in high regard. Please send me a photo of the wall you built in Myrtle Beach so I can include it in my piece. Appreciate it too if you could see if they are mentioned in Rye's club history - thanks.
Mark, yes the chip and run or putt option is taken away from you but as there are relatively few of these walls it is unlikely you would encounter more than one or two a round, and they do add to variety by forcing the lofted shot. Plenty of other occasions where you can play the run up shot unimpeded.
Bogey, the stone walls at North Berwick were there long before the course and the course laid out over and around them - they are a very dominant feature of the landscape there. Hard to compare them with the few low timber walls at Rye in either scale or extent. Clearly they are man made and inserted into the landscape, but I still think they are fun and quirky and add something to Rye (not that it needs adding to)