I don't really agree on the stereotype of "fast" or "slow" sex in different countries. Sex is something that is between the two people (excluding threesomes) and it really depends on if the two are ready or not for it.
A British couple, whom might be expected to be "fast", might not have sex until 6 months into their relationship if they don't feel ready for it yet. Whilst an Indian couple, whom people might think of as "slow", might have sex within a week.
It's quite unfair to have that kind of stereotype.
It is true that perhaps British are more open-minded about sex. Many people wouldn't mind talking about it.
You'll never know if a couple have had sex unless they tell you. But just because they don't openly talk about it, doesn't mean they are "slow" or haven't had it. We just assume they haven't because they didn't say, "OMG, I HAD THE BEST SEX LAST NIGHT!!"