The Master of the Winkler Epitaph
The Martyrdom of St. James
Second half of the 15th century
The image seems to blend the two episodes in the Golden Legend in which the saint is pushed to the ground. In the first episode, he is pushed from off of what the Latin says is a gradus, translated "platform" by Ryan and "lectern" by Caxton. This leaves him lame, but he lives and leads the Christian community for another 23 years. In the second episode, James is thrown from the pinnacle of the Temple; surviving the fall, he is first stoned and then beaten to death with a fuller's club.
The present image seems to use the gradus of the first episode and the clubbing of the second.
The Wikimedia page for this image says it is in the Museum of Fine Arts, Budapest, but I was unable to locate it in that museum's online directory to its collections.
Read more about St. James the Less.
Source: Wikimedia Commons