In 1287 Philip was chamberlain of Count Floris V.[3] That year he was granted the tithe of Wassenaar, except for the usufruct or dower of Oda, widow of Willem van Teylingen.

In May 1291 Philips was keeper of the seals of Count Floris V. At that time he was still a squire, and got granted the privilege that if he did not get a son, his oldest daughter could inherit his estate.

In 1336 the old burgrave asked the count of Holland to manage his estate because he was incapable due to old age.

[10] Ter Horst Castle in Voorschoten was held in fief by Philips' father Dirk.

In 1307 Dirk made Philips heir of Ter Horst Castle as part of a larger estate, and in 1309 Count William III did the same.

From 1863 to 1876 Prince Frederick of the Netherlands built a neo Gothic mansion on top of the existing foundations.

The exact reason is not that clear, but that the title burchgrave contains the word burcht, is no coincidence.