Out again with the young field assistant, who wanted to know why the beach had 'gone'. Ever tried explaining tides to a 2 year old? So in the absence of sand, we looked at lichen:
A closer look at the rock showed something distinctly fossil-esque, at the lower right of the following pic (and slightly out of focus, as the field assistant was tugging at my leg at the time which is hardly conducive to good macro photography):
Not like anything I've seen in the Jurassic shales and sandstones hereabouts. The rock is from the boulderclay undercliff which is a remnant of the last ice age. The boulder is probably an 'erratic', picked up from the west coast of England and dumped here when the glaciers melted. West coast rocks are far earlier in the geological sequence than our mere 190 million year old cliffs and scars. Off to the Natural History Museum field guides to see what it might be.