This is an unusual work for London-based collective greyworld, in that they normally base their sculptures in urban spaces. This one however, can be found on the Ridding Wood Trail and consists of seven oversized keys embedded in trees along the walk. The rhyme at the start of the trail explains:

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"Seven trees there are to find

And in each one a key to wind

Ten turns it takes to make the tree

Reveal its secret melody

Look up above and you will see

Hidden keys in the canopy!"

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In 2012, greyworld installed a giant sun in Trafalgar Square for one day, which used 210,000 watts to illuminate the entire square for three hours after sunset.