British Prime Minister Boris Johnson has apologized after a government ethics investigator criticized the U.K. leader and his staff for failing to disclose messages he exchanged with a donor about financing the redecoration of his official residence.

Christopher Geidt, the independent adviser on minister’s interests, wasn’t informed of the messages last spring when he investigated the so-called “cash for curtains” scandal. They came to light in early December as part of a separate inquiry by election regulators.

While Geidt said the new disclosure didn’t change his finding that Johnson had not violated the ministerial code, he expressed “grave concern” that the