In 1256 the Bishop of Rochester, Lawrence de San Martino (Lawrence of St Martin; r. 1251-1274), obtained the canonization of St. William by Pope Innocent IV. A beginning was at once made with his shrine, which was situated first in the crypt, then in the northeast transept, and attracted crowds of pilgrims. At the same time a small chapel was built at the place of the murder, which was thereafter called Palmersdene.
Remains of this chapel are still to be seen near the present St. William's Hospital, on the road leading by Horsted Farm to Maidstone.
Anyone seen the remains? I can't find anything on the internet or aerial mapping sites.