It was partly a social experiment, which he plans to write up in a book.
It was also partly giving expression to a desire to enjoy the fun of dressing up - a desire that society had repressed for most of his 46 years since he began to absorb the social norms of acceptable gender behaviour as a young child.
"Men's clothes tend to be more functional and practical to wear," he said.
"Women's clothes are more sensual. They are a delight to wear.
"As a male, I am able to experience all the wonderful things that women can wear, to be able to go through the transformation that women can go through with clothing, makeup and so forth.
"It's a pleasure. It's an aesthetic quality that I think all of us at some level enjoy, whether we want to acknowledge it or not."
Dr Cremin has adopted the name "Ciara Cremin" when he wears a dress, but he doesn't want to actually be a woman in a biological sense.
"I have no desire for a uterus," he said.
He is in a heterosexual relationship and his partner is supportive of his cross-dressing but also welcomes the fact that he is fluid in his gender and often still wears masculine clothes.
"Typically a heterosexual woman would not find a man dressed as a woman attractive," he said. "It's important that we are attractive to our partners."
He doesn't even want to "pass as a woman" when he dresses like one. He wants to be seen as obviously a man in a dress, in a deliberate challenge to the social norm.
"By not 'passing', I draw attention to the fact that gender is a fluid concept," he said.
"There is something profoundly unfair about a society in which men are so restricted and can't express themselves as sensuous beings, they can't indulge in different styles of clothing, they can't play around with makeup and do those transformations that many women like. I think we need to liberate ourselves from that kind of repression."
Men typically don't see you as a competitor any more, and women tend not to see you as a predator. It's almost like it becomes more relaxed.
Dr Cremin is a published critic of many aspects of Western materialism, with books to his name like Capitalism's New Clothes and iCommunism. His latest book, Exploring Videogames with Deleuze and Guattari: Towards an Affective Theory of Form, examines (among other things) the appeal of violent and often misogynistic video games to adolescent males who are trying "to work out their masculinity".
He has played "hundreds of video games" himself since his youth.
But by cross-dressing, he is deliberately "renouncing" the masculine power that young gamers and men in general are often under pressure to exercise.
"Men typically do have the greater power," he said. "It's men who deal with economic issues. So that masculinity which is cultural becomes power and control. To renounce masculinity is like you want to renounce power and control."
He has found that dressing as a woman has changed the way people interact with him.
"Men typically don't see you as a competitor any more, and women tend not to see you as a predator. It's almost like it becomes more relaxed," he said.
"Men tend to be more expressive, more tender, and women are often more expressive about the things that they like - I've had so many conversations about makeup and clothing.
"When people's sensitivities change, it changes the way you relate to yourself, so I think I've been more at ease with myself. I feel more relaxed, less alienated, less frustrated.
"When I first crossed that threshold and stepped into the street, I didn't think too deeply about the implications in a lifelong sense, but it soon became apparent that this was more important than just the clothes.
He said it would be very difficult now to just dress in masculine clothes in public. "So I think it would be very difficult to go back. I think it will be lifelong."
