hi keith, i'd say it's game over with your canary island date palm. if the center has rotted and you can pull the middle of the plant out, there is no chance of it making a recovery in the uk, even if the root ball and a couple of fronds still look ok. they are very slow growing and it will take years for it to recover. the canary island date palm is a master at "sulking" when not treated right. it could remain un-responsive for years, yet still be alive. i'd start again if i were you, if you actually want to see one grow and achieve good height and grow more fronds. they take long enough to grow as it is, so your wasting your time watching one with a rotten center! classic sign of frost damage or over watering. people flood these trees thinking it will make them grow faster, they have an excellent root system that is designed for seeking out the slightest bit of moisture. these trees grow in egypt and dubai where there is basically zero rainfall! uk rainfall is more than enough for them, so only water once when you plant them. but from my experience with growing these, rotten center is most likely frost and extreme cold damage. i'm not saying your tree has died keith, but unless you can plant it in florida for a while it aint gonna get any bigger!!