Is the empress tree good forage for bees?

[Zante]

Have they flowered yet for you ?

Looking at them online large flowers. For Bee forage the compact multi flower heads are better.

I haven't noticed any around London but I might have just missed them, and anyway it is still a little bit early for them to be flowering.
Yes, they are excellent forage for bees. They are the providers of what is called "acacia honey", that is why I was considering the possibility of planting a few around where I keep the bees, but if they're invasive I'd rather not.

EDIT:
You were asking about the Paulownia, right? (I need a facepalm smiley)

 

[Goran]

What about black locust?

I mentioned above, but after reading a bit about it it seems that it could be considered invasive, since it's a fast grower and spreads easily.
Is it considered invasive? I remember it was part of the landscape in Italy where I grew up...

I like the fact that it lets more light through than the average tree, so you can plant shrubs directly under it, and that it is a nitrogen fixer, so it will fertilise said shrubs.

I don't know for your climate, but here black locust when weather behave it can give great yields. It is considered that for 1ha of black locust forage, bees can gather 1000kg of honey.. It could give 10 kg per day if conditions are OK.
Invasive.. Well, fast growing and very easily slip off into firewood or as pier for the fence..
Now when rain loose the grip, some scent of black locust can be felt in the air. If it can survive next 2 days, I could hope for some extraction of black locust honey afterwards..