Alexander McQueen has branded claims it copied the Duchess Of Cambridge's wedding dress from another designer as "nonsense" and "ridiculous".
The label is being sued by Hertfordshire-based bridal designer Christine Kendall, for reportedly taking inspiration from her ideas after she submitted them to the palace.
Originally reported in The Sunday Times, Kendall allegedly sent an outline of her ideas for a 1950s-style dress to the Duchess, five months before the royal wedding in 2011, and claims she received a letter of gratitude from the palace.
But when the wedding took place, she alleges she spotted similarities between her sketches and McQueen creative director Sarah Burton's final design.
Now, five years later, Kendall has issued legal proceedings at the Intellectual Property Enterprise Court .
In the letter Kendall received back from the palace in 2011, an official wrote: "Miss Catherine Middleton has asked me to write and thank you so much for your letter of 18th November enclosing bridal gown designs.
"Miss Middleton was most interested to see your work and very much appreciated you taking the trouble to write. Should she wish to see more of your designs I will of course be in touch."
However, a spokesman for the Duchess told The Sunday Times that she had never seen Kendall's sketches.
Kendall's lawyer stressed that the claim is not against the Duchess and there "is no allegation of wrongdoing against the palace".
A spokesperson for Alexander McQueen also denied Burton had ever seen Kendall's sketches in an official statement.
"We are utterly baffled by this legal claim. Christine Kendall first approached us almost four years ago, when we were clear with her that any suggestion Sarah Burton's design of the royal wedding dress was copied from her designs was nonsense," they said.
"Sarah Burton never saw any of Ms Kendall's designs or sketches and did not know of Ms Kendall before Ms Kendall got in touch with us - some 13 months after the wedding.
"We do not know why Ms Kendall has raised this again, but there are no ifs, buts or maybes here: this claim is ridiculous."