English Heritage archaeologists have been digging at the Isle of Wight's only medieval castle in a bid to answer more questions about the area known as the Privy Garden.

The aim is to date the Privy Garden wall more accurately and understand when it was built and why this substantial wall was constructed along the east boundary of the garden.

"The re-opening of the entrance to the Privy Garden provides a timely opportunity to address some of the questions raised by the first archaeological dig here two years ago,” said English Heritage archaeologist Michael Russell.

“We are trying to find out how old this substantial wall is, why it was built in the first place and who was in residence at the castle at the time that it was built. It was possibly constructed under the orders of a captain of the Isle of Wight."

The earliest record of the garden wall is on a castle plan dated around 1700. However, archaeological evidence suggests that it could be considerably older, dating back to at least the 15th century. An original entrance to the Privy Garden was blocked up during Princess Beatrice's tenure as Governor of the Isle of Wight at the end of the 19th century when it was transformed from a kitchen garden into a pleasure garden.

"We are also looking at the bailey which is the area within the castle walls,” added Michael. “Part of the bailey has been separated off by this wall and we would like to find out what this enclosure was used for and when it was created.”

Layers of soil on either side of the wall are very different, which also appears to suggest that the bailey was divided during the 15th century - possibly by the huge masonry wall.

A magnificent example of a Norman motte-and-bailey castle, Carisbrooke Castle was built on an isolated chalk hill, which had previously been used as a high status burial ground in the 6th century.