In my Man, Myth & Magic encyclopedias I found the following.
It's an image of a foot washing. It is listed under the entry of Pentecostalism. The description of the image reads:
"Among some West Indian Pentacostalists the washing of each other's feet is an established rite. Pentecostalism has shown a special appeal and in Britain the most vigorous sects among the West Indian population are Pentacostalist."
Foot Washing Ceremony