I have been in touch with the publishers of Cochrane Shipbuilders. It would appear that, Gilbert Mayes, one of the authors of the book, heard about the research Ken Bagnall had done in the sinking of the Bromelia. It is the same information as Walter supplied with the link he gave. One comment that was made is that a U-boats KTBs may have only been written up after the patrol, if so the sinking of the Bromelia may have been overlooked.
Michael