Slightly off topic, but here goes.
When my brother bought his current house, in deepest rural Kent, the previous owner was there to hand over the keys.
This house (cottage really) has an inglenook fireplace, and at the time it had a basket fire in it. Anyway the guy points at the fire and says "I've left you the ashes". Sure enough there was a massive, compacted pile of ash under the basket. Thinking this was some weird Kentish house-handing over ritual, my bro just said "Cheers mate!" and made a mental note to hoover the lot up as soon as the last guy was out of the door, which he duly did & thought no more about it.
The fire was a pig to light & then when it did light, it burned the wood really quickly & hardly kicked out any heat. He was moaning about this to one of his new neighbours in the pub & this guy said he'd come round & have a look.
He rocked up, looked at the fire & said "Where's your ashes? Didn't that w4anker leave you the ashes? It takes months to build them up properly! The inconsiderate b4stard". (apparantly the previous owner wasn't well liked in the village...)
Turns out that the ashes work as a bed for the fire, making the wood burn slower & helps radiate the heat.....
He has a wood stove in there now.