For 17 years at Burberry, Christopher Bailey has rejoiced in rain. It is, after all, both quintessential British weather and the perfect setting for a trenchcoat. But for his last catwalk show for London Fashion Week’s biggest brand, the sun came out and Bailey’s reign ended beneath a rainbow.

The show opened with Adwoa Aboah in rainbow stripes on a white silk skirt and closed with Cara Delevingne under a rainbow fake fur coat. Puffa jackets and hi-top trainers came with rainbow stripes, and a trenchcoat and a blanket cape in a technicolour version of the distinctive beige check. This season the Burberry check is rainbow-hued, a symbol of the firm’s financial support for LGBTQ+ charities.

The check is to Burberry what the union jack is to Britain. Bailey’s last act as Burberry designer has been to lay a rainbow filter over it, rewiring a look once associated with 1990s football terraces to stand for tolerance and diversity. It is the final chapter in nearly two decades of compelling storytelling in which he transformed an on-the-ropes coat-maker into a global fashion player. And, through Burberry, he has reimagined what Britishness looks like.

“Fashion needs context,” said Bailey after taking his bow. “There are so many questions being asked in the world now: about our values, about the way we live, the way we consume. I wanted us as a big organisation to make a stand for something. It is a way for me to try and make some sense of all this chaos.”

The show began with Memories by Bronski Beat and ended with Don’t Leave Me This Way by the Communards. All the disparate elements of Burberry’s history were represented: trenchcoats and silk evening dresses nodded to high-fashion highlights, while shellsuits and plastic visors acknowledged the label’s place in the history of streetwear. But when the standing ovation came, the applause was for the man, not the clothes. This was the Fashion Week equivalent of a testimonial football match.

As well as reviving Burberry, Bailey played a major role in boosting London Fashion Week. When Burberry moved its show from Milan to London in 2009, it signalled the city’s new status as a serious player.

In the first decade of his tenure, “doing a Burberry” entered the fashion lexicon as a new phrase to mean bringing a limp brand back to life. As well as boosting its sales figures, Bailey made it stand for something bigger than fashion. The identity that he art-directed was a mission statement about modern Britishness, with a mood board stretching from Ernest Shackleton’s explorations to Virginia Woolf’s Orlando.

The check was sidelined during his first years as the label set its sights on high-fashion credentials, but as the brand gained confidence, the check was rehabilitated. Last year it reappeared on baseball caps and zip-up jackets, looks once seen as a downmarket drag on a luxury brand.

The past seven years have been rockier for Bailey. After becoming the first non-founding designer of a leading brand to be given business control, combining CEO duties with creative direction, he faced a shareholder revolt when investors voted against a remuneration report which gave him shares worth nearly £15m.

Last year, he relinquished the CEO role and returned to focusing solely on design. The new chief executive, Marco Gobbetti, who previously led Céline in Paris, has said that Burberry must “evolve and try new things … ask ourselves tough questions, and be bold in all areas of the business”. In October, Bailey announced his departure, clearing the way for a new era.

At the end of the show Bailey said he was proud of having brought “a design point of view” to Burberry, and felt “great excitement” at exploring new possibilities for himself and seeing where his yet-to-be-announced creative successor – possibly Phoebe Philo or Kim Jones – would take Burberry.