The 200-year leak inquiry: Source of water that's blighted stately home by Parliament architect since 1835 is found at last

Published: 01:04, 25 April 2026 | Updated: 01:08, 25 April 2026 It's a leak that has plagued the grand country mansion for almost two centuries. Year after year, moisture seeped into the roof of Kingston Lacy house - confounding experts who carried out numerous reports on the issue. But at last they have got to the bottom of the problem, discovering a design flaw by a renowned master architect. Sir Charles Barry, best known for his work on the Houses of Parliament, was commissioned to design a new cupola to top the 17th-century country house in 1835. However, he designed the windows of the dome-shaped structure to be glazed 'inside out'. According to the National Trust, this was possibly in order to look more attractive to visitors to the Dorset home.  This meant the protective putty was put on the inside of the glass instead of the outside. It caused moisture to leak in more easily, rotting the timber window frames, destroying the paintwork and requiring regular maintenance over the years. Documents show work was carried out to repair the cupola while the Bankes family owned it. Since 1981, the National Trust has also had repair campaigns. After years of investigations, the team at the Grade I-listed property identified the exact area of the leak as the windows of the dome-shaped structure were glazed 'inside out' Sir Charles Barry, best known for his work on the Houses of Parliament, was commissioned to design a new cupola to top the 17th-century country house in 1835 After years of investigations, the team at the Grade I-listed property has identified the exact area of the leak.  Work will take place in stages over the next year. The team will also investigate and repair defects in the leadwork around the base of the cupola, which is also allowing water to seep in. A National Trust spokesman added: 'What's changed is that detailed surveys, long-term monitoring and historic research now give us a clear understanding of what's really causing the leaks which means we can now fix the problem once and for all. 'The current works are aimed at stopping this cycle of decay rather than repeatedly treating the symptoms.' The comments below have not been moderated. The views expressed in the contents above are those of our users and do not necessarily reflect the views of MailOnline. By posting your comment you agree to our house rules. Do you want to automatically post your MailOnline comments to your Facebook Timeline? Your comment will be posted to MailOnline as usual. Do you want to automatically post your MailOnline comments to your Facebook Timeline? Your comment will be posted to MailOnline as usual We will automatically post your comment and a link to the news story to your Facebook timeline at the same time it is posted on MailOnline. To do this we will link your MailOnline account with your Facebook account. We’ll ask you to confirm this for your first post to Facebook. You can choose on each post whether you would like it to be posted to Facebook. Your details from Facebook will be used to provide you with tailored content, marketing and ads in line with our Privacy Policy.