The "New House" 'annex' in itself had approximately 360 rooms and was built primarily to accommodate the multitude of people that accompanied royalty when they visited.
[7][9] On taking the title in February 1629, the 5th Marquess downsized, moved the family out and waited until returns from his extensive estates all over England allowed him to start restorations.
The 4th Marquess's entertainments almost bankrupted the family, maintenance of the house fell behind, and the design of such a large brick-built (and somewhat experimental) complex after one hundred years had its problems with dry and wet rot, broken windows, leaking roofs, and keeping the various wings heated.
To send a message to other Royalist supporters, Cromwell returned to London and there was a Parliamentary decree issued that anyone could take from the estate, and therefore local villagers were encouraged to remove bricks from Basing House, and these materials were reused in homes in the surrounding area.
John Paulet had his estates confiscated and was sent to the Tower of London on a charge of high treason, which was later dropped, and the site of Basing House was returned to him by Charles II.
His son Charles Paulet, 1st Duke of Bolton, became wealthy again as a consequence of his support for William of Orange during the Glorious Revolution.
[14] Parts of the basement or lower ground floor remain, including the wine cellar, brick doorways and archways, bread ovens, salt alcoves, side rooms with surviving vaulted roofs, a vaulted tunnel, and even some original plaster and mortar.
A UK Heritage Lottery Fund scheme has supported significant upgrades and renovations in recent years.