Gonzo,
Fair enough, and far be it from me to second guess a highly paid Captain , but I've come across more than a few flightcrew who assume that because there is no NOTAMed closure, both of our runways will always be open to landing aircraft, and thus think that committing to LHR is a far safer proposition than divving out. I'm saying that often it's not.
But the point is that there are two runways available when the decision is made (amongst all the other criteria) - if not, then we're diverting!
Once again, the point needs to be made, when you arrive at your diversion airfield, the same risk exists that something may close the runway. Worst case scenario, the guy landing in front of you. Then what?
It feels like there's some "holier than thou" theme running through this thread with those decrying the decision to burn diversion fuel at destination taking the moral high ground.
I'd still love to know why diverting is safer.