No growth on Montana Rubens

[Zitouna]

My clematis Montana Rubens is in its third year. Had lots of growth and flowers last year. But not a single sign of growth at the moment - can’t see any buds at all. We’re in London, in a reasonably sheltered spot, so I was thinking it might be dead?

Next door cleared their garden in late summer last year. Nothing else on the boundary seems affected (including another clematis) - but now wondering if maybe they sprayed and caught the Montana. What do you think?

I’d not give up yet, but I would prune it done to about 30cms. there’s nothing lost at this stage. Then the plant is not under stress to produce growth higher up. Montana’s are quite resilient. I’ve had one massacred by tree surgeons, only to find it growing stronger than ever.
Unfortunately if it has been sprayed then that’s it. Other things around it seem ok.