After being handed a P45 mid-speech by an audience member, a chronic coughing fit and then having the sign behind her fall to bits, it might seen a minor faux pas.
The Telegraph, heroically, tries to justify it:
After divorcing her husband Diego Rivera, Kahlo painted Self Portrait with Cropped Hair in 1940. The picture, showing her wearing a black suit and with a very short haircut, was widely interpreted to mean that Kahlo was sending a strong message to men: I am independent and I don't need you.I prefer a simpler explanation.
Might Mrs May have been willing the 'naughty boys' in her party to understand the very same?
I imagine she wore it because she had little idea who the artist was and just thought it looked stylish and interesting. If she had a clue, I doubt she'd have been so silly as to wear it for the biggest speech of her life.
Just another fail in a day - a whole conference - of fails.