Yes, they shut down LHR for an extened period when the Etiopian 787 started to burn, and they shut down when BA started to throw cowlings around, and they shut down when BA crashed short of 27L, and if my memory serves me right, they shut down once for a VS partial gear up landing. I'm sure there have been other closures as well.
I expect a major international airport to keep open when there is an accident on one runway and the other one is clear. If not, they should limit everyday operations to one runway only.