[Baron]

Underside of blocks on lip of top roof festooned with crosses in chalk; tick marks (spank)? Or warning of imminent death for belay if pulled upon?

[ChrisC]

Underside of blocks on lip of top roof festooned with crosses in chalk; tick marks (spank)? Or warning of imminent death for belay or random walker if pulled upon?

The latter I think:  http://ukbouldering.com/board/index.php/topic,15600.msg271521.html#msg271521

[Baron]

Searched for that, thanks.