Hello Douggym
Do you want the good news first? Well I'm sorry there isn't any.
I contacted Kew this morning and they told me to contact the Tree Advice Service on premiun rate number 09065 161147 (�1.50 per minute). I declined.. Their website www.treehelp.info had a link however to The Arboricultural Association at Ampfield House, Hampshire. A knowledgable chap / expert there informed me that he was aware of the problem and that quite a few other people had contacted him about this matter. He stated the problem was 'country wide' The CAUSE IS NOT KNOWN. He said he would ring some research people, or whatever, and get back to me with any further info. if indeed there is any. At the time of writing this I haven't heard back from him. Green leave Robinias are not suffering same fate, so he said.
I asked if my own tree with some small growth had any chance of surviving and he seriously doubted such a possibility.
I am trying to contact WHICH and WHICH Gardening to inform them of the problem if they don't already know about it. The matter needs to be given publicity in order to elicit the cause. The tree was developed, I understand, in Holland and I wonder if anybody there knows the cause.
If you or anybody else finds further information then I would be grateful to know. I will update on any more info I get. WHICH has just rung me and I have informed them about this problem.