Thanks for your informative contribution, Ironman.

I've no wish to demonise climbers/boulderers, but when it comes down to important rock art sites such as Tle Langdale Boulders/Copt Howe/Chapel Stile, then I think it's better to err on the side of caution.

As you say, boulderers have been climbing over this site for years, yet the rock art was only re-discovered in 1999. Important markings could have already been erased. We don't know.

As for the hardness of the rock, well, we're all aware of stone steps which have been badly eroded by feet stepping on them over time. I would presume that the act of climbing the near-vertical rock would act in a more erosive manner than simply stepping on it.

Baz