Disaster has struck Wendy's tree

I'm very sad to report that Wendy's tree appears to have died. About 10 days ago I found all its leaves brown and shrivelled. Less than two weeks earlier it was green, although in hindsight I noticed the leaves seemed a bit curled up. The man who planted it thinks it may have been infected by Sudden Oak Death Syndrome, and samples have been sent for testing.
SODS (an appropriate name, that!) is a fungal disease that mainly infects oaks in California, and some other trees and shrubs including rhododendrons, which are thought to be the main vector. It isn't widespread in the UK and British oaks are anyway thought to be much more resistant than American varieties.
I'm not completely convinced this is the explanation, but I'm no expert. And anyway this may not be an English oak - apparently it came from a nursery in Holland, and when I looked more closely at the trunk yesterday I was surprised at the number of scars where side branches had been cut off as it grew from a seedling. Again, I'm not an expert, but I would not have expected so many side branches below the main crown on an English oak. But what is clear is that the tree is not healthy.
I will arrange for a replacement, but this can't be planted till the winter. In any case, we need to know why this one has sickened before putting another into the same ground. More to follow...