The entrance of Bräuninghöhle (1623/82), found by CUCC in 1977. The painted number is clearly visible on the rock Jont Leach (one of the explorers) is standing on, and is still clear in 1998, though now supplemented by a bolted-on metal tag just to the right of the entrance (roughly just below where Jont's right elbow appeared 21 years earlier).
Photo © 1977 - scanned from CU 1978 cover