Ancient Druid Altar for Druid Sacrifices?

The Juicee News Daily had an article about "Haunted Places in the United Kingdom."

The article talks about the Chislehurst Caves as "a labyrinth of dark, eerie mysterious passageways which have been hewn by hand from the chalk, deep beneath Chislehurst. There are over 20 miles of caverns and passageways, dug over a period of 8000 years. The vast complex of caves are a maze of ancient mines originally carved out in the search for flint and chalk. They are divided into three main sections, Saxon, Druid and Roman. Each section was later connected by digging joining passages. There is a haunted pond deep within the caves, the legend goes that a white lady appears and floats across the water. For many years there was a reward for anyone who could spend the night alone down in the caves, to date there have been some unsuccessful attempts, but so far nobody has been able to do it.. There is also an ancient Druid altar where sacrifices were carried out in the Druid section of the caverns."

It certainly looks like a place I'd like to add to my itinerary when I travel to the London area. Their website doesn't appear to have any photos of the alleged altar though. I haven't seen any clear evidence that ancient Druids actually performed sacrifices. I wonder what evidence they have....