Thanks for all the wonderful replies. Not unexpectedly, as with many questions asked on the forum there is no one simple straightforward explanation . Danielle is a female persona I create for myself. It is a feminine illusion but not a delusion , I still realise it is Dave underneath all the makeup etc. The illusion is easily shattered when I have answered the phone while being Danielle and I see Danielle in the mirror but Dave's very male voice is talking. That's when the huge incongruity hits me as Danielle is strictly a stay at home girl and has never experienced interacting with anyone in public. Overall I have to truthfully say I am content with the balance I maintain with my male/female brain.

Special thanks to GretchenM , I will definitely investigate the book "Gender Mosaic"