David Cameron was overheard by microphones saying that 'the Queen purred' when he gave her the result of the Scottish Referendum vote.
This is surely not literal, but a figurative use of purr.
I did notice that Oxford Dictionaries records a meaning 'speak in a low, soft voice, especially when expressing contentment...'.
But that is not the same as 'purring', the early 17th century origin of which word was imitative of the contented sound a cat makes.
Would people be pleased or offended at having been said to have made a sound usually reserved for cats?