Really interesting to know. I wonder how much of it is in relation to trust of .uk compared to others? I also suspect our geographical size and available delivery companies have something to do with it. We have good infrastructure and can have goods delivered within 24 hours relatively cost effectively. Not so easy for larger countries without spending more.
Last week, the ten millionth .co.uk domain name was registered. When it comes to the internet, having the letters UK attached to your company name is highly desirable.