I have a mature vine in a garden that we took over a few years ago. It's has been harshly pruned over the last couple of years now we realise it looks dead
.
Should vines have buds/leaves visible on them now (I'm in London btw)? It all looks black and dead. There's no sign of life anywhere except from where a low branch was accidentally pruned today where it looks all fresh inside and there's a steady flow of a clear liquid.
I fear that we chopped off the last remaining living stem of this plant today 
Is there anything I can do to help it? I've watered the base. Is there anything we can feed it?