On what dimmer setting it was used for most of its life ? Could it have been dimmed occasionally to the point where it had no halogen cycle going ?

Did it get heavy use? Good that it's failed quietly though. The most common failure I had with these in the open fronted halogen floods was the caps corroding and failing rather than the filament actually breaking like this.

@Ash: Mostly at full brightness considering my mum needs to see clearly the music sheets when she is playing the piano - it has seen some mid brightness dimmer setting and thanks for pointing out that running it too dim for a long time can shorten the lifespan of the halogen linear lamps @Beta 5: Yes it sees a lot of use cos my mum plays on the piano almost everyday and she hosts piano lessons