This church is the shrine of the Dorset martyrs, whom I have mentioned before.
As the website states, the Dorset martyrs are among the "clouds of witnesses" of the English Martyrs:
Of these, eight are associated with Chideock. Seven were put to death and are known as the Chideock Martyrs. The eighth, John Jessop, was put in prison for his Faith and died there. Their portraits are displayed above the nave in the Church.
Fr.Thomas Pilchard was a Jesuit and despite being banished, in 1586 he returned to England and became Chaplain at Chideock Castle where he was concealed. While he was here, he made many converts including William Pike, a carpenter in Chideock. Both were put to death in Dorchester and were beatified, together with Jessop, in 1987.
Blessed John Cornelius was a friend and Chaplain to the Arundells at Chideock Castle. Around Easter 1594, a servant betrayed his presence and he was arrested along with
Thomas Bosgrave, a nephew of Lady Arundell, and two servants, John Carey and Patrick Salmon, all of whom had tried to save Fr. Cornelius. All four were executed at Dorchester on 4th July 1594 and beatified in 1929.
Blessed Hugh Green also became Chaplain to the Arundell family and was martyred in 1642 after being arrested at Lyme Regis as he tried to escape to France. He was beatified in 1929.
More about the history of the shrine and pilgrimages here.