I watched a program on Netflix about the restoration of a P51 Mustang (the same one that later crashed and killed passenger). The restorer said that the life of a combat Merlin was very short and few managed much more than a couple hundred hours. They were, along with the aircraft they were fitted to like Spitfire, Hurricane, Lancaster, Mustang etc, regarded as a consumable and performance / power more important than longevity.
Some info - https://groups.google.com/forum/#!topic/rec.aviation.military/8Qn_ZFAUBBU
We will hear about it, but I'm not sure how much I'll be able to tell you when we do unfortunately. The bbmf merlins are rebuilt every 500 hours, not sure how long since these were fitted.
As far as I know the problem has only affected one hurricane, and the rest have been grounded as a precaution but that was yesterday's news so it may have changed.
The griffin engined mk19 is u/s for other reasons by all accounts too, we were hoping for a display at the show we are at this weekend in Lytham, but no such luck. As an aside, if anyone is around lytham tomorrow, we will be ground running a merlin throughout the day and I'll be bobbing about if you want to come say hi