As you say Barry, information about KD is very hard to find. I think the firms main activities were rebuilds and overhauls. However, they did build some new organs. The earliest reference I can find is 1932 when they built a residence organ for Laurence Ide Esq, Chestnut Lodge, Cobham, Surrey. NPOR ref N13456. Which went to Holy Trinity, Brompton. NPOR ref N18003.
There is a Dutch site which lists some of the other instruments they were involved in, but I suspect these were mostly rebuilds Https//orgelsite.nl.
During my short time in the firm the flagship instrument was Holy Trinity, Brompton - when Robert Munns was organist there. I recall there we constant problems with it, resulting in almost weekly call outs.
I remember years ago having a conversation with John Norman about Reginald Davidson. John said that he could never understand how such a lovely man could build such dreadful organs!