It's a Campsis - radicans, I think. Otherwise known as Trumpet Vine. It must have enjoyed the hot summer we've had as I believe they like a hot spot to flower in.

It is Campsis. Remarkable that it has survived for so long unless the roots have gone out the bottom into the soil below which I suspect they have.

I would be surprised if they haven't gone into the soil--they are usually hard to keep up with in a pot!

Thank you so much for your responses - much appreciated.