Old St Lawrence Church is a ruined building in Ayot St Lawrence, Hertfordshire, England. It is a Grade II* listed and dates back to the 12th century.
The building was partially demolished in 1775 by Sir Lionel Lyde. It was replaced as the parish church by a new St Lawrence Church, a neoclassical building on another site.
Although Lyde is commemorated at the new church, the old churchyard remained in use. Burials include Rudolph Lambart, 10th Earl of Cavan (1865 – 1946), whose maternal grandfather was rector of Ayot St Lawrence. The Earl was a Field marshal and his resting place is registered by the Commonwealth War Graves Commission, although he was not a casualty in the normal sense of the term.
Coordinates: 51°50′16″N 0°16′02″W / 51.837738°N 0.267306°W