Marks & Spencer has insisted it has no problem with the stock levels of its critical autumn fashion range despite having already sold out online of sizes in some of its key lines.

The department store retailer, which has launched a star-studded ad campaign featuring artist Tracey Emin and Oscar winner Dame Helen Mirren, is thought that 75% of the clothes advertised on in-store postcards this week has sold out in at least one size, according to the Independent.

For example, the coat that supermodel and singer Karen Elson’s wears in the ad campaign was unavailable online in size 6 and 8, the jumper featured sold out in size 6, 8, and 10, and the treggings she wears sold out in sizes 8, 16, 18, 20, 22 and 24.

However, a Marks & Spencer spokesman said: “Our customers have responded very positively to the campaign and the products featured have been extremely popular.

“Some of the high fashion lines have sold through very quickly – much to the delight of the customers who bought them first. Overall we have more than 50% more product than in previous years and it is being replenished more frequently to maintain stock levels. Customers are now eagerly anticipating the next phase of the collection which will land online and in stores in October.”

Last year under pressure chief executive Marc Bolland vowed to buy more stock after customers were left disappointed because buyers had failed to order enough knitwear advertised in its posters

Bolland said earlier this year that the website is the new flagship store for the brand, offering services such as click and collect and next-day delivery.

Honor Westnedge, a senior retail analyst at Verdict Research, said: “It sounds as though they’ve underestimated stock levels, and I think they need to avoid customer disappointment by pushing people to the website if the stock isn’t available. They’ve gone in all guns blazing with this really high-profile campaign that they’ve invested lots of money in promoting it. But M&S is not Topshop or Zara, and is new to fast fashion and that quick supply chain.

“The strength of their competitors’ supply chains is one of M&S’s biggest weaknesses.”

M&S’ make-or-break autumn collection has so far received a positive reaction for its style and quality.