Like every other successful team, England's strategy is to build up a young team well ahead of each world cup. They very nearly got it right in 1991 but were narrowly beaten by Australia in the final. They got it exactly right in 2003.
Have a look at the splash graphic for England. You can see that from 1988 they start building and maintain or improve their win percentage year after year until finally peaking in 1992 - a year too late as it turns out. Leading up to 2003 they do exactly the same, the difference being that they peak at exactly the right time.
Now, leading up to 2015 they show exactly the same trend. Apart from a small downward turn in 2012, they're definitely building and it looks like they're getting it right for the second time.