Hmmmm, maybe you're right Dove
scratch and sniff, looks like rhubarb to me
well spotted there before the pickaxe moved in
That's Iris unguicularis, desirable, winter flowering, likes a warm corner
Agree with Berghill, Cotoneaster horizontalis
Can you post a photo, it would help give an idea. Scraping the bark might not give an accurate answer if the plant is newly dead.
Di the leaves go brown then drop off (or stay on) or did they drop off while still green?
Not sure how long they live but it's a lot longer than 5 years if they're happy.
I can't see much root there.
Pittosprum I think but couldn't say which
I can't claim responsibility DW, you said Thunbergia, by then I was determined to find the answer