Why do we British struggle at world sport?

It's a question I constantly ask myself. Take the Davis Cup for instance. Despite millions of pounds being pumped into tennis development in the UK, our Davis Cup squad, minus Andy Murray have slumped down the world ratings following our recent defeat by Lithuania. We are now in danger of playing our tennis at a level equivalent to  what could only described as the non-league standard of football. But tennis is not the only sport we struggle at. The summer and winter Olympic games are at times embarrassing for our teams, although we did better than we have ever done at the last summer games, which is encouraging. Is our lack of success down to lack of talent or lack of proper funding? The United States, Australia, Germany all have a winning mentality and yet we, despite plenty of effort fall way short of their endeavours. We have the football World Cup finals coming up this year in South Africa and our hopes of progressing to the latter stages of the competition are better than usual. That is unless we fall foul (pardon the pun) to the dreaded penalty shoot-out competition, of which we are notoriously bad at, going out of competitions on more than one occasion. Should we provide adequate funding for up and coming British athletes of all sports with a scholarship similar to other countries or is the money spent on such things a vote killer for politicians? I would like to see  sport being actively encouraged and promoted more in schools. I saw the demise of these types of activities when I was at school years ago, whereby you would have a Headteacher with no sporting interests, running down (again pardon the pun) sports facilities. I think sporting activities in schools is essential for the well being and development of children, but competition seems to be a no-go area for some authorities these days. Still, I will try to remain optimist and look forward to the day when the UK start leading the field (oops, there I go again) in every sport they enter or am I being delusional? Anybody agree or disagree or got any ideas how we can improve?