One princess who designs clothes, one official heir who insiders whisper isn't up to it, and a monarchy quietly looking for a way out. Thailand has reopened its most delicate subject - who will sit on the throne.

The state visit of Thai King Rama X and Queen Suthida to France in late June - only the second of his reign - could have stayed a purely diplomatic ceremony at the Élysée. But the spotlight landed on someone else: Princess Sirivannavari, the king's youngest daughter, who accompanied the family through the whole tour. Her increasingly prominent presence has reignited the very debate the Thai court would most like to avoid - the succession.

Her story is unusual on its own. She is the only child from the king's second marriage who was not stripped of titles when he cast out his former wife and the rest of the children. Brought back from England to Thailand as a child, she grew over the years into one of the monarch's closest figures, while also building a career as a fashion designer. It's a position almost nobody in a monarchy holds - at once on the outside and at the very heart of the family.

Behind the ceremonial glitter lies real uncertainty. The official heir is Prince Dipangkorn, but questions about whether he's capable of carrying the crown keep circling him. The death of an older half-sister, once the presumed heir, after three years in a coma, muddied the line of succession further. A 1924 Thai law lets a woman enter the line of succession if there is no male heir - but only with parliament's approval. Hence the speculation that Sirivannavari herself could emerge as a candidate.

For a reader in our part of the world, this is a reminder that the question of who follows the king is simple nowhere - not in the ancient monarchies of Asia, and not in the Balkans, where the succession of power was often settled with blood rather than protocol. The difference is that Thailand does it behind closed doors, through fashion exhibitions and state banquets, while the real battle for the throne is fought in silence. And silence, as everywhere, usually means the decision hasn't been made yet - or that it has, and nobody dares say it out loud.