Found under rocks on low tide. Each 'blob' was approx 0.5 cm wide
No interactions present.
...definitely, not sure which mollusc though.
I think Robert's ID is close to the mark, Mark. And there are probably two.
I have found that such pictures out of water almost never lead to a successful ID. But Nudibrancs tend to expand into life in only a little water, say with a small piece of weed - then, they are even more difficult to photograph!
Note that Andy here http://www.ispotnature.org/node/393749 had the same problem.
Take a look at mine (which may ineed be the same species) but the details are seen.
http://www.ispotnature.org/node/370097 picture are taken in very shallow water.
Next time then.
THREE MARINE PROJECTS
Lat/Lng: 51.3, -3.3
OS grid ref: ST1467