An early flagwaver by Ealing Studios, stars John Clements, Leslie Banks, Jane Baxter and Ann Todd with a sterling cast of supporting actors including the Michaels Rennie and Wilding.
I'm reveiwing it here because the frocks are all designed by the then newly formed Incorporated Society of London Fashion Designers. (Inc Soc)

Jane Baxter

Michael Wilding gets the girl (Jane Baxter)
This body was formed by the government and comprised many British couturiers some of whom had been conscripted in to the forces. Its main purpose was to promote British fashion abroad and various collections were put together to take to the Americas.

It's a pipe!
Anyway, the designers got together for this film as a means of advertising, all those listed in the
opening credits were well established couturiers except Maison Arthur who were a high-end ready to wear house, I think that they supplied the background frocks.

John clements, Ann todd & Betty Marsden

Betty Marsden in Lachasse
The film follows the story of a ship (played by HMS Ark Royal) from its launching until the beginning of the war, John Clements and the 2 Michaels are navy pilots whose exploits in the air and in the nightclubs of London are the main focus of the film. Clements is disgraced but takes-it-like-a-man and ends up being in a good position, when the war breaks out, to pass on vital intelligence to the navy. The ladies provide love interest and musical entertainment and Ann Todd gets to die heroically for her country (in a very nice dress). She also becomes an 'Ionic column' for ther nightclub number. Which is a total WOW.

Betty Marsden and Ann Todd disguised as a greek column

Ann Todd (detail)
There is no attribution of individual dresses and the only one I can identify with any certainty is the suit worn by Betty Marsden, It is classic Lachasse.

Ann Todd in a travelling suit arrives on a Greek island (somewhere in the Med)

Ann Todd just about to be menaced by Hugh Williams