Charles Spencer issued his first joint message from him and his new girlfriend Cat Jarman on Saturday morning.
The words were penned alongside a heartfelt video from the MS Society encouraging people to donate to the charity and have their donations doubled if they do so by Sunday 27 April.
Alongside the video, the ninth Earl Spencer wrote on X: "My partner @CatJarman and I are absolutely delighted to support @mssocietyuk in their fundraising drive this month. 'Such a great cause' doesn't cover the half of it: what they are doing is crucial to so many."
This is the first time the Earl has shared a joint public message with his new love whose own MS diagnosis was revealed in December.
Cat is currently suing Charles' estranged wife Countess Karen for the misuse of private information.
Last month, the Telegraph reported that in new court documents from the proceedings, Cat expressed she and her children experienced "significant distress" due to speculation around the case, as well as feeling "compelled to publicly disclose the fact of her MS."
© InstagramBack in December, Cat gave an interview to the MailOnline where she discussed her MS diagnosis, a move she felt necessary to "bring an end to the harmful speculation and gossip which had been percolating online," as stated in the claim.
The claim states: "In these circumstances, the claimant wished to regain some of the autonomy and control over her medical information."
In Karen's 11-page defence, in which she accuses Charles and Cat of having an affair, details of Cat's MS were "volunteered" by Mr Jarman because he "plainly believed" that it was relevant to his wife’s behaviour and the fact she had embarked on an affair.
It was, according to Karen, "a relevant and integral part of the picture" and it was never suggested that the diagnosis was a "secret".
Charles' split from Countess Karen
Charles split with Countess Karen last May announcing the news in the Sunday Times.
"It is immensely sad" he told the publication. Adding: "I just want to devote myself to all my children, and to my grandchildren, and I wish Karen every happiness in the future."
© GettyIt is thought that Charles and Karen's marriage broke down in recent years amid the strain of the Earl's memoir, A Very Private School, in which he detailed physical and sexual abuse while at boarding school.
Now, Countess Karen has moved out of Althorp House where they lived with the daughter Lady Charlotte, 12.
In February, gave fans a glimpse of her "temporary" new home with a stunning photograph from its sprawling grounds.
Alongside the image she wrote: "Well…at long last, three weeks ago, we finally moved into our temporary new home. Still waiting for the horses to arrive - hopefully next week! Doesn’t quite feel like home without them."
Days later, she revealed her horses successfully arrived at the property sharing another glorious photo of one named Jack making the most of the grounds.
