Boris Johnson has apologised "unreservedly" after Speaker John Bercow accused him of making "inappropriate and frankly sexist" comments to Emily Thornberry.
The Foreign Secretary was given a dressing down after referring to his opposite number as the "Lady Baroness whatever" in an apparent reference to her husband Sir Christopher Nugee.
Mr Bercow took exception to the comment, telling Mr Johnson it was not appropriate to speak in such terms, and drawing applause from the Labour benches.
The Speaker said: "I don't want to be unkind or discourteous to the Foreign Secretary but I say on advice, as the clerks swivel round to me, two things.
"First of we all, we don't name call in this chamber.
"Secondly, we do not address people by the titles of their spouses. The shadow foreign secretary has a name and it's not Lady Something, we know what her name is and it is inappropriate and frankly sexist to speak in those terms.
"That is the end of the matter. No matter how senior a member, that parlance is not legitimate, it will not be allowed and it will be called out."
Mr Johnson "apologised unreservedly" after the telling off, adding: "I heartily tender my apologies to (Emily Thornberry) if she was offended by what I said and I meant no harm, and I apologise unreservedly to her if I have offended the feelings of (Ms Thornberry)."
Later in the question session Foreign Office minister Harriett Baldwin attempted to defend Mr Johnson, saying he did not have a "sexist bone in his body".
Ms Baldwin, who made the comment while answering a question on promoting education across the globe, said: "As a passionate feminist and without a sexist bone in his body, the Foreign Secretary is an advocate for education and has discussed with the Secretary of State for International Development and the Secretary of State for Education among others."
Speaker John Bercow responded: "I know she won't take it amiss, but the Foreign Secretary doesn't need to be defended by her and I know she wouldn't argue with the chair, she'd come off rather worse."