Mass-reproduce it, gassify it, and make everything from the rocks to the surface-critters capable of regret and sorrow, along with understanding.

It might nit change much, but you can cause unimaginable suffering, and have a following of hyper-intelligent animal-critters, who may resent or adore you.

The rocks might even be sorry enough that they will bring london up, rather than crush it in adoration to another part kf the city.