The term actor is not neutral but masculine.
There is no gender-neutral word in this context. Another example is aviator (m), and aviatrix (f).
An example of multi-gender words include spokesman (m), spokeswoman (f) and spokesperson (n), or perhaps flautist and musician as examples of truly gender-neutral words.
In his letter (M Star October 18), Bob Mitchell is quite right to point out that his granddaughter is female and to use the appropriate term of gender reference is in no way derogatory to the person concerned.
I am quite sure that Ms (if that's not insulting) Kennedy does not regard herself as neutral but feminine and therefore deserves to be addressed as such out of respect to her gender.
Andrew Barrington
Swindon