Here is my old tree that may or may not be Exochorda serratifolia (exochorda is neighbour's suggestion). In my garden book, most of the other exochordas look like Spirea Bridal Wreath and the only tree-variety I can find on the net is serratifolia. It does have a tan-coloured bark - I mean, the part that's not covered in lichen is light brown and smooth. What do you think? The hardly-serrated leaves look rather small for a prunus and it has no fruit. The flowers are prunus style, though.
Just checked Amazon, the way you do, and see that Tropical Connections is for sale already though not due to be published until 1 June. So that's exciting. It's cheaper at the Book Depository, by the way. Click on the right if you fancy knowing more.