It's a nest but not what we expected

After initial interest last year, from the Blue Tits, the nesting box was not a great success  in it's location in the dead Eucalypti tree.
https://www.blipfoto.com/entry/2164853448657339891

We moved it down lower and against the garden wall, thought the Robins would like it lower down but no interest at all.

We've noticed that we seem to have a few bees around in the garden and this morning I found out why it's more than usual. They have commandeered the bird nesting box for themselves. 
I'd love to take the top off to see what's inside but Marlane has warned me to wear gloves and long sleeves. She knows me too well obviously!