Slightly off topic, but for an adopted child, Thomas/Ruby looks a lot like dad Christopher Guest during his "Spinal Tap" days. The face & bod are chubbier, but an image search of Guest from the "Spinal Tap" era shows that the resemblance is strong. IMO, it's unmistakable.

Because Thomas/Ruby is adopted, he cannot inherit his father's barony to become Lord Hayden-Guest, 6th Baron Hayden-Guest, though he & his sister can use the title, The Honourable. I wonder if Thomas would have "transitioned" to Ruby if the rules allowed him to become Baron Hayden-Guest himself. Wikipedia uses The Hon. before the names of both Curtis-Guest kids: The Hon. Anne Guest and The Hon. Ruby Guest.

Maybe they used a surrogate and didn't want people to know about it.