When I started work out on the airfield at LHR in the early 1980's hardly a week went by for each shift to experience a runway closure due burst tyre. It was a well-practiced routine to scramble everyone to go and pick up the debris and open ASAP. Tyre technology has improved so much in the intervening years that it is now a really rare event.
We also had 'shoulder' runway slot periods with a reduced hourly rate so that events like this could be soaked up by the system; that's also a thing of the past. The slot situation is now so tight that any disruption will knock-on for hours or probably the rest of the day.
The BA cancellation policy isn't confined to LHR, the same applied to BA's LGW short-haul operation; better to suffer the short-term pain which actually minimises the number of people affected, rather than what the charter airlines do, which can knock delays on for days in the height of the season, affecting thousands of pax. Then again, you can't really 'cancel' IT charter, you have to carry the pax eventually...
TheOddOne