Retailer Marks & Spencer today (17 April) admitted a failure to buy deeply enough on its best-selling women's wear lines led to a decline in fourth quarter clothing sales.

Speaking to journalists, chief executive Marc Bolland said: "What we didn't have enough of was our best selling lines, what we did was, we kept stock too tightly".

The retailer also changed its product mix, increasing its 'good' range from 14% to 19% of clothing products and reducing the proportion of 'best' products from 35% to 20%.

"If you change the mix you have an impact on revenue, and that's what you're seeing back. We are addressing this element very strongly to get more into 'better' and 'best' as well," Bolland added.

The retailer was also caught out by the weather during the quarter, selling around 100,000 items of knitwear when it could have sold around 300,000.

"February was extremely cold," said Bolland. "We didn't have enough knitwear, coats, and we have seen that clearly on Autograph, the higher priced [brand], was very short on jackets, on outerwear, and we could have probably sold around 20,000 extra items during that month in terms of outerwear."

Bolland also said that while the retailer was "bang on trend" with its more fashion-driven styles, recording more than 50% growth in printed tops and blouses, it simply "didn't have enough."

He emphasised the difficulty in responding quickly to a sudden change in the weather. "You just can't react to it" as customers would rarely buy knitwear and coats after winter. "February is never a month in retailing here when we would focus on knitwear and outerwear."

"If you asked me again next year are you going to put a huge amount of coats and knitwear in February - no I probably would not, but I would make sure I had a bit of stock in case the weather changes or cater in the supply chain that I can react a bit faster to it."

The M&S chief said the difficulties were exacerbated by the lead times associated with sourcing knitwear and outerwear from the Far East.

"If you talk about knitwear and the supply chain, you know that knitwear is not produced around the corner, so knitwear is particularly [made in] Asia so therefore the supply chains will never be able to reflect that demand in four to six weeks."

Despite the difficulties, the retailer has no immediate plans to bring its sourcing closer to home or increase UK manufacturing.

Instead, he blamed the problem on the fact it "did not buy deep enough in certain areas" over two months. "We have a lot of areas that performed well, we have one area where we could have done better, let us not read that we need a structural change in the business."

As far as the company's UK sourcing credentials are concerned, Bolland said M&S is the largest buyer of UK finished products and materials.

"I think we shouldn't read into this, that we should start massive manufacturing in the UK. I should however give an indication that in GM [general merchandise] we are already the largest buyer of finished product, materials and clothing in the UK," he said, adding that the retailer already purchases some GBP200m in finished products and materials each year.

The comments came as M&S recorded a 0.3% decline in UK clothing sales in the quarter ended 31 March. General merchandise sales, including clothing, declined 1.2%, while food recorded a 3.1% increase. Consolidated sales rose 0.8% over the quarter, despite international sales declining 2%.

Analyst opinion of the stock shortages was mixed, with Investec's Bethany Hocking describing the retailer's women's wear performance as "weak" and "worrying".

Conlumino analyst Neil Saunders noted: "The decline in general merchandise sales is of some concern given the relatively weak comparatives in the same quarter of last year.

"In clothing M&S serves a wide range of customers and in our view the offer needs to be executed with greater clarity and focus both to make it easier to shop and more enticing to consumers; this is especially true in women's wear."

Meanwhile, Singer Capital Markets analyst Matthew McEachran described the retailer's issues as "fixable".

The retailer's share price was down 3.6% to 354.3p at 13:19 BST today.