Seriously, I think he'd probably die at what she would expect him to spend on an engagement ring. He strikes me as quite close with his money, as well as being frugal on things like watches. He probably thinks, like any sensible person, that £50k is a stupid amount to spend on an engagement ring. Whereas he would doubtless expect a £500,000 zinger like Amal Clooney's. Imagine her face falling as she sees the teeny tiny diamond!