The Coffin Stone is the name given to a large sarsen stone at the foot of Blue Bell Hill near Aylesford in the English county of Kent.
Situated 400 m north west of the Countless Stones. It is a rectangular stone lying flat and measuring 4.4 m long and 2.8 m wide. Two much smaller stones lie nearby.
In 1836 local farmers found 'a sack of bones' underneath the stone, the only record of this is written, the bones are not able to be located and all other evidence is presumed destroyed. It is possibly the remains of a chambered long barrow, further archaeological excavation was carried out in the summer of 2008 and the evidence did not suggest this, but was inconclusive.
The Coffin Stone is the bigger Stone underneath.
The White Horse Stone is 2.9 m long, 1.65 m high and about 0.6 m thick and stands just off the Pilgrims' Way. Close by it are nine smaller stones that stretch to the west for about 10 m.
There is no evidence of a covering barrow and it has been suggested that these much smaller stones were moved from the neighbouring field by local farmers. Its identification as a chambered long barrow like the other Medway megaliths is therefore uncertain although the shape certainly resembles a chamber wall stone.
In local tradition this is also the burial place of the Saxon leader Horsa. The standing stone is also considered by some visitors to resemble a horse's head. Both these links have been suggested as the source of the name. A connection with the white horse on Kent's "Invicta" coat of arms has also been invoked. Locals at the nearby public house in the early 1990s used to refer to the White Horse Stone as "The Inga Stone".