The first model in the Paul Smith fashion show in Paris on Sunday afternoon wore a sharp suit. It was teamed with a tie covered in fish. This combination, of the classic and the playful, is one that Smith could almost patent. It continued throughout this show, which took place in a school hall. Square bags were made to look like the tins of mackerel found in Japanese fish markets and shirts were covered with a print of tropical shores.

The colours were inspired by flora and fauna found in the ocean; vivid orange, purple, red and yellow dominated. This is the second season that both men and women have been on the catwalk in the show, with 19 outfits for women and 28 for men.

Female and male models appeared at the same time, some wearing corresponding designs – a man and a woman wore similar Prince of Wales suits at the start of the show. Smith’s strengths are his tailoring and his sense of colour. Both were shown off here.

The coloured suiting worked well. And wrap dresses with hibiscus flowers were strong. The backdrop of multicoloured plastic subtly reminded the audience of the brand’s signature rainbow skinny stripe branding.

Smith had scaled back on this in 2014 for fear of overkill, but it’s slowly making its way back into the fold. Backstage, the designer, now 70, piled into a group of brightly dressed models for a photo opp. “Guess what?” he quipped to assembled press. “The collection was inspired by the ocean.”

He wanted it be light relief, “a bit of irreverence in these difficult times … I think at this time of year everyone is wanting to be in a seaside situation, not in a hot hall”.

Smith remembered buying trips in the 70s to New York and San Francisco to buy “vividly coloured” shirts for his Nottingham shop. He sold them to clubbers going to Wigan all-nighters because “they were great for dancing in”.

First founded in 1970, Paul Smith is now an institution of British design recognised throughout the world as a safe pair of hands for tailoring, with a bit of jolly eccentricity on the side. Smith himself is almost a national treasure; one relevant to a digital generation. He has 319,000 followers on Instagram, more than double that of his brand. He was knighted in 2000.

In December 2015, it was announced that the business would be streamlined. Once the business had 12 collections, now there are two - Paul Smith, the high-end collection as seen on the catwalk, and PS by Paul Smith, which has cheaper outfits.

This is an attempt to stem falling sales; the group turnover was down by 8.4% when the change was made. The most recent figures have yet to indicate whether the move has worked. Operating profits fell 63% to just under £4m in 2016, put down to a smaller wholesale customer base and shrinking markets in Asia beyond Japan.

Earlier in the day Lanvin showed a collection that mixed sportswear and casual tailoring. The collection, designed by Lucas Ossendrijver, built on a new direction for the house’s menswear from last season. Previously concentrating on an easy kind of tailoring, there was engagement with casual looks that could appeal to younger customers.

A growing trend in the menswear shows has been gorpcore, or outdoorsy functional clothing reworked for a luxury audience. That was present here too. Among oversized suits there were parka jackets, backpacks, bumbags and cagoules. They came in the pastel colour palette of that other millennial-friendly trend, the 90s.