In The Mousetrap, why does Christopher Wren say, "there's something very boorish about the English husbands"?

The architect Christopher Wren is the first paying guest at Mollie and Guy's new guest house. Immediately, Christopher and Mollie hit it off, though Guy is somewhat nonplussed, with the over-friendly architect paying Mollie a compliment on her beauty. Mollie is suitably embarrassed by his kind words and mildly chides him for being so absurd.
It's then that Christopher observes that Mollie's reaction is typical of English women: that whereas most European women take compliments in their stride, their counterparts in England find them a source of embarrassment. He then goes on to ascribe such embarrassment to the alleged boorishness, that is to say, rough and ill-mannered behavior, of Englishmen towards their wives, which apparently crushes all the feminine spirit right out of them.