Although the origin of the cave is unknown, its rediscovery is well documented. In August 1742 a workman dug a hole in the Butter Market to build
footings for a new bench for the patrons and traders. He discovered a buried
millstone and dug around it to remove it. He found a shaft leading down into the
chalk. When discovered, the cavity was more than half-filled with earth. The rumour was that there must be a treasure buried beneath the soil inside the cave. Several cartloads of soil were removed until bedrock was reached. The soil was discarded as worthless as it only contained a few old bones and fragments of pottery. Today's
archaeology could have analysed the soil in depth. The Reverend G North's description of a brown earthenware cup with yellow spots discovered in the soil filling the cave sounds like a well-known early
post-medieval type, no earlier than the late 16th century.Today the entrance is not by the original opening, but by a passage dug in 1790. The cave is at the junction of an ancient east-west track, the
Icknield Way, and the north-south Roman road,
Ermine Street. Icknield Way was used during the
Iron Age and traces of its side ditches have been excavated at
Baldock. It has been claimed to run from the Thames Valley towards East Anglia, although this has recently been called into question. The modern-day A505 between Royston and Baldock approximately follows its route. It is thought that the sculptures were originally coloured, but little trace of this is visible now; in the mid 19th century,
Joseph Beldam could still see the yellow dress of
St Catherine and the red of the
Holy Family. They are mostly religious images, such as the
Crucifixion and various saints.
St Lawrence is depicted holding the gridiron on which he was martyred. A crowned figure holding a wheel appears to be St Catherine, and a large figure with a staff and a child on his shoulder represents St Christopher. A figure with a drawn sword could be St Michael or possibly
St George. Another possibly religious symbol is the depiction of a naked woman known as a
Sheela na Gig. This figure is sometimes found on
medieval churches so its inclusion with religious symbolism is not out of place. There are a number of holes, sometimes directly beneath the sculptures, which are thought to have held candles or lamps which would have illuminated the carvings. ==Restoration==