Harrow, outer borough (1991 pop. 194,300) of Greater London, SE England. For centuries Harrow grew foodstuffs for London. It is mainly residential and contains parts of the Green Belt, areas set aside as parkland. Optical and photographic goods and glass are manufactured. The famous Harrow public school, founded in 1571, is in the borough. Among its graduates were the writers George Byron and John Galsworthy and the statesmen Sir Robert Peel and Henry Palmerston.