Lovely plant with gorgeous color.
King's Mantle (Thunbergia erecta)
Wow what a huge plant! Looks like a tree from the size of the stems! And the flowers are as you described! I can't wait for my T. battescombei to flower again, it is waking up from enduring winter in my sunroom.
I have 3 very large Thunbergias, right now they must be close to 6'. I let them grow to that height and then I cut them down to 4' at the end of spring. By the end of the summer, they can reach 6' plus so I have to prune them again. I have to do this with most of my plants, they tend to grow huge if I don't control them.
That's fantastic, jnana! At most I can expect my Thunbergia to get is 3 feet tall, but I am sure that is a container effect.