The common understanding of an "expert" in any field is of an individual who is recognised by others in their profession, working in the field, as an authority on a particular aspect of the subject. It is commonplace for an "expert" to have published or lectured widely on their specialised aspect of that subject.
With no disrespect to you, being also educated to post-graduate degree level myself, a Masters degree is a commendable personal academic achievement but the qualification alone does not even begin to suggest that a person ought ever to be considered an "expert" in their field.
I would never refer to you - or indeed myself - as an "expert" in our subjects simply because we possess a post graduate level qualification.
Philip's PhD suggests an even more "specialised" area of study than an M.A. - but on the subject matter he has been consulted for Creighton's latest publication, he ought never to admit or declare himself an "expert" for he has not been recognised by others working in that field (Creighton notwithstanding) to be an authority on that aspect of Egyptology.
Given this, I'm surprised that you think so.
If you maintain that you are indeed an "expert" in art then the expectation is for you to disclose where and what you have published and whom others might consult in your field to determine that this is, indeed, the case.
In anticipation of your reply,