Why are they doing that?

[armchairarborist]

i have to just nip out down to the yard and drop off some erm... woodchippings. where's me hammer and chisel?

[yewhunter18]

Haha yeah come get me I'll help 60/40 to me

[armchairarborist]

think its going on ebay as 'pot o gold', maybe someone will realise its true value?

[yewhunter18]

Haha maybe or just use it as chopping block

[Beardie]

It's the very rare cannonball tree, the fruit were highly prized during the Napoleonic Wars, to the extent that attempts were made to cultivate them on board ship.

Actually, if you want to see a really good bricked-up cavity, try Cambridge Botanic Garden.