Mark Fast's skin-tight dresses steal the show at London Fashion Week. Carola Long reports

If there is anyone out there who still thinks knitwear is just about comfy cardigans and keeping warm, they should take a look at Mark Fast. At London Fashion Week yesterday, the 28 year-old Canadian designer showed a spring/summer 2010 collection of cutaway knitted dresses that were more clingy than cosy.

In a clear statement that his designs are not intended only for very slim body shapes, the Central Saint Martins College-trained Fast sent out several of his figure-hugging designs on voluptuous models, alongside the usual willowy girls.

Having the body to pour into one of Fast's hot pink vest dresses, isn't enough though; you'll need serious attitude too. Many leave little – often too little – to the imagination. Cobweb and ladder-stitch knits in chocolate, lilac, black and shades of pink revealed inches of flesh, while some skirts barely covered models' buttocks.

Behind the degree of sensationalism inherent in such obviously sexual clothes, however, was a high level of skill and innovation in different knitting techniques, and the way these responded to the movement of the body, even if there was more than a hint of Alaïa in his designs. A tight, black vest dress came with tiny knitted tiers overlapped like roof tiles, which bobbed gently as the model walked. Fast may have a reputation as one to watch, but it will be interesting to see how he moves his aesthetic forward.

Fast's show was scheduled back to back with Mary Katrantzou, another young designer on the Topshop-sponsored Newgen programme. The focus was on bright, graphic prints – some inspired by animals, others by coloured glass – on clean shift dresses. Details such as a fan-shaped bodice on a zebra-print pencil dress mirrored the undulating curves of her hand-blown glass jewellery, which appeared in the form of cuffs and necklaces.

While yesterday was mostly about fresh design talent, the week will also see the return of big brands including Pringle and fashion giant Burberry, which is showing its new line in London for the first time in a decade. The 25th anniversary of London Fashion Week this season sees the return of many designers who had previously deserted the city for the shows of Paris, Milan and New York, and is billed as the best in years.

If the new guard's vision was appropriately modern, London Fashion Week veteran and Dublin resident John Rocha showed a characteristically wistful, romantic collection watched by Sarah Brown. The Hong Kong-born, London-trained designer's love of texture expressed itself in the sweetest skirts and hats adorned with silk georgette petals and leaves, and crinoline-like sculpted dresses made from stiffened white crocheted fabric.

Rocha's designs tend to be most effective on skirts rather than trousers; a ballerina-shaped petal dress dress was pleasantly girlish, while trousers with the same finish looked overly naive. However, anyone with a romantic sensibility would find it hard to resist his charmingly antique palette of old rose pink, tobacco, burnt orange, duck-egg blue and cream.