WIkipedia says he has a son, John, styled Earl of Dumfries, b. 2024. However, there is a missing citation.
I just checked GRO, and there is the recording of a birth for "John Zhisen CRICHTON-STUART" b. Q4/ 2024 in Kensington and Chelsea.
I'm going to do a separate post on this, to see if one of our intrepid group members can confirm this might be the new heir.
Thanks, pyvery.
Brooke