Kazz, have you tried shaving off a slice of bark with a stanley ? If there is life there it will show some green. You have seen the Monty Python parrot sketch haven't you ??? In my experience, I have seen rejuvenation via the roots.
Jazz, i had a lilac that'd been planted too close to the house. I wasn't wild about the color either, so i cut the thing back to a 3 foot stump, then dug the whole thing up. It then sat on my brick terrace, soilless, rootless, friendless for about two weeks. Very sad. But, it kept giving off little shoots of green from it's stump. Poor thing. I took pity on it & posted its photo on our local website. I found a taker for it & a year later heard it was happily growing in the guy's yard. Moral of the story: it takes a lot to kill a lilac.
