Discussions like this can get silly but one thing we all need to remember, young athletes especially if standards are to return to what they were, is what constitutes 'top class'.
Take Dave Lewis as an example from one of the many recently given. Top class road and track runner (so far as Britain goes) but not on the fells. Before someone pipes up that he once won the uphill trial, well 2 years ago Ian Holmes won Duddon when it was a Championship, and long races in the lakes are said to be HIS WEAKNESS! That's what makes a top fell runner, like I said we all have weaknesses but it's being able to run all the different types of races on the calendar that counts, not picking and choosing which courses suit you.
Likewise, 30min for 10K and 50min for 10 miles whilst they are very good times, are not top class. Dave Lewis ran 61:17 for the Great North Run, during which he must have gone through 10 miles in 46 odd. If people achieve these sort of times (50min 10 miles) and think they've made it (as someone hinted at this before on this thread...) no wonder we're falling behind the rest of the world as a nation.