Merchant Taylors' School is an 11–18 boys' public day school, founded in 1561 in London. The school has occupied various campuses. Since 1933 it has been at Sandy Lodge, a 285 acres (115 ha) site close to Northwood in the Three Rivers district of Hertfordshire. The school has 1100 students between the ages of 11 and 18. The school is an all-through school from age 3 to 18 after merger with Northwood Prep School in 2015.
Founded in 1561 by Sir Thomas White, Sir Richard Hilles, Emanuel Lucar and Stephen Hales, it was one of the nine English public schools investigated by the Clarendon Commission set up in 1861, and successfully argued that it should be omitted from the Public Schools Act 1868, as did St Paul's School, London, the other day school investigated by the Clarendon Commission.