Where on earth is the key lock for the trunk on a W204 estate?

I've taken the battery out to charge, but can't get back in the boot now...
Is there something simple I'm missing??

 

I've found the answer, for anyone else that's interested.

There's no key latch on the outside of the boot/trunk, it can only be accessed from INSIDE the trunk.
You need to open the doors using the key blade, pull down the rear seats and climb in.
There's a small hole next to the latch that the key blade goes in to release the latch, and you push the trunk from the inside.

So practical...