Further to my earlier note about the suggested ancient till at Lydstep, I have been back there today to check it out -- and it is very impressive indeed.
The first record of an ancient till at this site is from Arthur Leach, in his papers and manuscripts held in Tenby Museum:
I also visited the site and published a brief record of it in 1974. The key location is a little peninsula that extends southwards from the "heel" of the big peninsula. Here, by a freak of nature, a vast expanse of cemented limestone breccia has been protected from extensive marine erosion. An area of at least 30m x 20m supports a most unusual -- and slightly surreal- -- landscape of concreted ridges and hummocks of limestone debris (mostly sharp-edged fragments which are partly frost-shattered and partly natural scree slope accumulations) on an undulating rock platform about 20m above sea-level. I agree with Leach that this is not a wave-cut platform -- it is too high, and it does not have a wave-cut notch against an old cliffline. I have struggled a bit to work out where on earth all this shattered scree has come from, and have come to the view that it cannot all have come from the cliff slope to the north. I think this is the floor of an old karst dry valley like the one that runs northwards from the western edge of Lydstep Headland today. The southern side of this valley has, I think, been completely lost to marine erosion. This is an indication of the great age of the breccia and everything that lies beneath it.