I wandered down the garden for a peek at the tree wasps this evening and was surprised to see the queen sitting at the entrance. I guess it was too warm inside the nest. The nest has grown quite a bit since the last time I put a photo here ( http://365project.org/roachling/365/2014-06-20 ).
They'll leave of their own accord soon enough. Wasps don't reuse old nests so once summer is over, they'll vacate this one.