The sub-manor of Rowbarns lay on top of Crocknorth Hill and stretched down to the main road. It lay in Effingham Parish but had belonged to Merton Abbey until the Reformation.
The Agmondesham family lived there from 1360 to 1598 when John Agmondesham died without an heir and it was inherited by his sister who owned East Horsley Manor. The two manors then merged into one.
The present house called Rowbarns Manor predates Lovelace, but it is not certain who built it, possibly one of the Currie family. After the large house on Crocknorth Hill was demolished, a small house in Greendene was extended and a castellated wing was added so that it would be a suitable residence for minor gentry to rent.
When Lord Lovelace bought East Horsley Park it was already clad in flint, as was Rowbarns Manor. Perhaps this gave him the idea to build the rest of the estate in flint.
Rowbarns Manor does not have any of Lovelaces eccentric decoration on the outside, but in an inner courtyard there is an underground rainwater-fed tank with a pump, typical of many Lovelace houses, and some of the fireplaces are surrounded by tiles which are also found in Horsley Towers. This may be one of His Lordships early improvements when he did not apply much decoration, or he may have improved the property between tenants. It was finally sold to a private buyer in 1919 when the estate was broken up.
One of the former buildings in the old farmyard is now a dwelling known as Rowbarns Cottage.