Horsham is not mentioned in Domesday Book. The W tower and the NW corner
of the N aisle appear to be remnants of an earlier church which was
substantially rebuilt in the 13thc., probably in 1231, when the advowson passed
to Rusper Abbey. Rusper, a nunnery founded by William de Braosec.1200,
also possessed the churches of Warnham, Ifield and Selham.