The informal noun brothel-creepers, also brothel-creeper shoes, denotes soft-soled shoes.

This noun, sometimes shortened to creepers, refers to the stealthiness that those shoes permit (cf., below, quotation from the San Francisco Examiner (San Francisco, California, USA) of Sunday 3^rd January 1943).

The following is from Men’s style: What to buy now, by Teo Van Den Broeke, Style Director of Esquire UK, published in the London Evening Standard (London, England) of Friday 8^th December 2017:

FINDERS CREEPERS

Defined by an ultra thick, flatform crepe sole with a suede or leather upper, brothel creepers were originally worn by Teddy boys in the 1950s. Now, CEO of Dazed Media and former Mr Moss, Jefferson Hack, has teamed up with 30-year-old British brand Underground to bring the creeper back. Consisting of six ultra-distinct styles, my pick from his limited collection is the black-soled number with white and peach leather upper.

JEFFERSON HACK X UNDERGROUND
brothel creepers, £180 per pair
(underground-england.co.uk)

The earliest occurrences of brothel-creepers, brothel-creeper shoes and creepers that I have found are as follows, in chronological order:

1-: From the caption to the following photograph, published in the San Francisco Examiner (San Francisco, California, USA) of Sunday 3^rd January 1943:

‘CREEPERS’ FOR AFRICA PATROLS

DESERT BOOTS—Tough South Africans who use these boots which they call “brothel creepers” don them at night for sorties to cut Nazi desert communications and destroy gun positions. Boots have rubber soles to cut noise to minimum.
—Associated Press Photo.

2-: From New Deal For Police Sleuths, by R. T. Jeffriess, published in The Sydney Morning Herald (Sydney, New South Wales, Australia) of Saturday 18^th June 1955:

For a long time, there has been a tendency for the amateur—and in this category must be included the private investigator—to shine at the expense of the police force.
The real amateur is generally portrayed as a rich, brilliant dilettante complete with classical education and impeccable manners; never as the snooping, scandal-loving busybody he would be if he actually existed in our society.
The private investigator is likewise glamourised and becomes a tough, intuitive member of the jungle. Never is the private eye shown with his keyhole stoop and brothel-creeper shoes.
While the amateurs in crime fiction enjoy this elevation, the police, on the whole, are forced to remain dumb cops.

3-: From Crop of Crooks, by ‘Cassandra’ *, published in the Daily Mirror (London, England) of Thursday 6^th November 1958:

The gaols are crammed—over 27,000 men are locked up—and every day we read stories of bolder, more arrogant and more cunning criminals.
For the most part they are young men who work in gangs—they are so youthful that it is not a valid reason to blame the war for this bountiful crop of crooks.
I was in a magistrates’ court some time ago when one of these adolescent miscreants was charged—together with four other downy-haired gorillas—with a ferocious case of robbery with violence in the Midlands.
The youngest of them couldn’t have been more than nineteen years of age.
What fascinated and horrified me was his deportment in the box.
He swaggered, grimaced and winked around the court—signals that were gleefully returned by a collection of yobbos of both sexes who had turned up to see the performance.
And to this tousle-headed lout, expensively dressed from his draped jacket to his remarkable footwear (known as “brothel creepers”), it WAS a performance.
It was HIS performance.
HIS big day.
HIS personal appearance on the stage of crime.

* ‘Cassandra’ was the pseudonym used by the English journalist William Neil Connor (1909-1967) for his column in the Daily Mirror.

4-: From The Daily Sikeston Standard (Sikeston, Missouri, USA) of Friday 18^th September 1964:

In a long article in Men Only, a British monthly, Warwick Charlton wrote about class, status and the climate of snobbery.
In England, family comes first. After that, money helps. The right schools, colleges and universities are important, as are the proper clubs in mature years.
[…]
And finally (this is England): ‘The correct uniform for Sunday drinks is a scarf, dirty old sweater, cavalry twill trousers, and brothel-creeper shoes.’