My first thought was ' Bulldog Drummond 'for the first clue you give, p-potter, but I cannot make it work.
As to Mexican Hairless, I cannot make that one work either..so I'd love any help from anyone who can explain it.
As to the 'Working with Mrs Black (7)' clue, I cannot make anything of it at all. I could see that Oncilla would work if it were Miss Black, but not with the clue as it is.