Charles Spencer shared some fantastic news with his followers on social media on Sunday.
To his side was a white Land Rover decorated with the Red Cross logo and flag, which the Earl explained in his caption.
He wrote: "Delighted that The White Ship fundraising talk at @AlthorpHouse on Friday afternoon raised £12,000 for the #BritishRedCross #thewhiteship."
The White Ship is the talented author's latest book, and it tells the true story of the sinking of the titular vessel in 1120 and how that altered the course of British history.
WATCH: Princess Diana's brother Charles Spencer thrills fans with stunning wildlife video
Charles' followers responded to congratulate him on raising so much for charity in just one day. One wrote: "What a fantastic achievement - congratulations!"
Others added: "Fabulous! Such a wonderful cause. Well done all," "That is fantastic, great stuff," and simply: "Brilliant!"
Another of the 56-year-old's fans, meanwhile, complimented him on the content of the event, replying to say: "It was a very interesting lecture and I am enjoying the book."
The Earl is custodian of the stunning family estate
Charles, who often takes the time to chat with his followers, responded: "Thank you, Jane - very kind."
Althorp House is a tourist favourite, being one of England's grandest stately homes and the childhood home of Princess Diana.
The Earl is now custodian of the beautiful estate, which has been in the Spencer family for hundreds of years and includes over 90 rooms and 550 acres of land.
During the pandemic, he has kept fans around the world updated with news from the residence via social media, most recently sharing a video of the home's resident peacock, Tim, enjoying a walk on a large expanse of grass.
The Earl captioned the short clip: "Tim the Peacock taking things easy this afternoon. A little foraging in the sunlight keeping him busy."
Make sure you never miss a ROYAL story! Sign up to our newsletter to get all of our celebrity, royal and lifestyle news delivered directly to your inbox.