Koutsoudakis, who has worked for the retailer for five years, previously handling marketing and visual merchandising across clothing, home and beauty, was speaking on an Advertising Week Europe panel called "Reflecting diversity in creative output", chaired by ISBA director of public affairs Tanya Joseph.
She highlighted M&S’ desire that "pretty much everyone in the UK sees him or herself in our output".
"It’s a live conversation at every touchpoint and every piece of communication, not just in our Christmas and big fashion campaigns. We have a conscious discussion, are we being inclusive of our audience through every application? Can we find that balance between aspiration and inclusiveness?"
Despite this longstanding focus, making sure the retailer’s creative output is inclusive is "not second nature", but neither is it "a struggle", Koutsoudakis said in a response to a question from Joseph.
Rather, it is "a constant live conversation" taking place within the company and with its creative agency partners, and with the understanding that sometimes "we are going to get it wrong, we just have to learn from it".
Due to having 33 million customers and the existence of Facebook, "we get told every day that we’re doing something wrong", Koutsoudakis added.
"But if it’s genuinely a value that the business believes in and your intent is in the right place you’ll overcome the executional mishaps when they happen.
"We don’t always get it right, we don’t always get it back from the agency right, it is a conscious live conversation that we need to go back to, but it is fundamentally part of M&S, it is a core value.
"So we pick ourselves up when we get it wrong, when we’re not inclusive on size, we get a lot of that, that we’re not always inclusive on size, because we try to strike that balance between aspiration and actually being inclusive on size, but we acknowledge when we get it wrong and then we move on from it."
As an example of getting inclusion right, Koutsoudakis talked about a Breast Cancer Now partnership campaign M&S did last October featuring real survivors of breast cancer telling their stories, which were formed into a poem by its ad agency Grey London.
"There was a genuine connection between the people and the group was diverse. The words were their words. It was a hugely powerful piece of content for us in terms of M&S thinking about different types of people and even in similar situations how people who themselves are different are constantly peeling that back," she said.
The panel also featured Nationwide chief marketing officer Sara Bennison and Fearless Futures director of programmes Sara Shahvisi.