Knowledge of his wife Kate Middleton’s cancer diagnosis appeared to weigh heavily on Prince William during his last engagement.

The Princess of Wales announced her grim diagnosis in a video message posted on the Waleses’ official social media accounts on Friday.

She revealed that the cancer was discovered during post-op tests after undergoing a major abdominal surgery in January.

Though, the exact timeline of diagnosis is unclear, it could be presumed that the Prince of Wales was aware of the diagnosis during his public engagement last week, where he held an audience for his homelessness project.

Writing for the Daily Mail, royal author Rebecca English claimed to have observed William from the sidelines at the event.

She noted that the future King appeared to be carrying “the weight of the world on his shoulders,” adding: “I couldn’t quite put my finger on exactly what it was, but there was a slight sadness around the eyes and, noticeably, a loss of weight.”

The royal correspondent continued: “How remarkable that he has even been able to do half of what he has undertaken publicly in recent months – even carrying out investitures for his cancer-stricken father – given everything that has been going on behind the scenes.”

“I know he is angry, frustrated and, yes, deeply disappointed, at what has transpired over recent weeks,” she explained of the deluge of conspiracy theories online. “‘When will it all stop?’ he is said to have asked.”