In the last few weeks, as illness has sidelined two of Britain’s most visible royal figures, Catherine, Princess of Wales, and King Charles III, one member of the family’s frontbench has stepped into the vacuum: Queen Camilla.

Last week, she traveled to the Isle of Man to deliver a speech on Charles’s behalf and met with public officials and community groups. She then flew to Northern Ireland, where she visited a bakery and butcher shop, attended a literary event and accepted salutes at a military parade.

Camilla, 76, smiled for the photographers, joking on Thursday that a camera-friendly toddler who upstaged her visit to the butcher shop was a “natural.” She betrayed neither the strain of taking care of a cancer-stricken husband, nor that a day later Catherine would announce that she, too, had been diagnosed with cancer.

It is the kind of twist of fate that royal watchers savor: Camilla, the woman whose very existence once seemed to threaten the stability of the royal family, has emerged as a stabilizing force during a major royal health crisis. At times recently, it has felt as though she was carrying the entire House of Windsor on her shoulders.

“This is a vulnerable time for the royal family, where their human frailties are fully on display,” said Arianne J. Chernock, an associate professor of history at Boston University and an expert on the modern British monarchy. “Camilla’s own background and training can help her in these circumstances.”