LONDON — On London’s Bond Street, home to some of the most expensive retail space in the world, only one store needs to instigate crowd control, the luxury brand of the moment: the Italian fashion and accessories powerhouse Gucci.

By midmorning on a wet and windy British midsummer day, burly security guards had erected velvet ropes along one side of the store’s gilded floor-to-ceiling windows. Inside, a dozen black-clad assistants raced around on lurid magenta carpets, serving the 20-some customers on the ground floor. An orderly line made up mostly of tourists formed outside, many of them looking hungrily through the corner store’s glass panes.

It is this sort of slavish devotion from Gucci’s customer base that resulted in the brand’s reporting a 43.4 percent increase in sales in the first six months of the year. That, combined with a sales increase of 28.5 percent from its sister brand YSL, propelled its parent group, Kering, to record growth in revenue and profits for the period.

The Kering results came 24 hours after LVMH Moët Hennessy Louis Vuitton, the world’s largest luxury group by revenue, said strong growth in Europe and Asia had bolstered sales by 12 percent in its second quarter. Profit for the first half of the year also grew at its fastest rate since 2011.