I come from an Edinburgh branch of Warrenders (see the other message posted) whose geneology is well-documented in Edinburgh city records. My Grandfather was Sir Victor Warrender, who later became Lord Bruntisfield (the title has now passed to my Uncle, who still lives in Edinburgh). My father and I are always curious to discover items of family genealogy, and as you rightly point out, the name is not common and in rarely appears on lists etc. We have a fair amount of documentation and family history, as the line traces back well into the 18th Century and before. Pease contact me if you have anything of interest.