A size-12 Hayley Morley led the team at the end of the show
A stylist and casting director have left a London Fashion Week show over a decision to use average-sized models, a fashion boss says.
Amanda May, managing director for Canadian designer Mark Fast, said there were "creative differences with regards to the casting of those girls".
Fast broke fashion convention by putting three size 12 to 14 models on the catwalk on Saturday.
"There was a team change and we're glad we stuck to our vision," said Ms May.
Ms May said stylist Daniela Agnelli and casting director Natalie Hubbard stepped in at the last minute to help out.
She said the decision to feature three models from the agency 12 + UK was neither politically motivated nor a publicity stunt.
"The decision to use the fuller girls is something we have been talking about," she said.
Mark Fast's show took place on Saturday
"There's this idea that only thin and slender women are able to wear Mark's dresses and he wanted to combat that.
"We wanted women to know they don't have to be a size zero to wear a Mark Fast dress - curvier women can look even better in one."
She would not divulge exactly what was said on Thursday night before the freelance pair left the team, saying "we don't want to talk about the ugly bits, we want to talk about the beautiful bits".
Fast is a 28-year-old knitwear designer known for his figure-hugging mini-dresses.
His clothes used to be one size fits all but his spring/summer 2010 collection features garments in different size groups.
However, they are not categorised numerically to "challenge traditional notions of fit and idealized body shape".
He has also been involved in All Walks Beyond the Catwalk, a photography exhibition featuring models aged 18 to 65, from sizes eight to 16.
This is where he met Hayley Morley - one of the models he used in his show.
The exhibition opened at Somerset House on Friday, the new central London home of London Fashion Week, which runs until Tuesday 22 September.