This is a Scheduled Ancient Monument. The ‘Magic’ website confirms that it was included in the schedule in 1925 as ‘Wiltshire 130’ and is now scheduled in the national monument register as ‘28993’, and is described as “Bury Wood Camp hillfort and earthwork enclosure 750m north of Raffinwood House”.
A two page report (PDF document) on the fort and enclosure is available via the ‘Magic’ website, at magic.gov.uk/rsm/28993.pdf
Large multivallate hillforts such as this are relatively rare in England, with around 50 examples recorded.