M&S hopes Sienna Miller’s sold-out sequins will help wow the city

Marks & Spencer investors are hoping to be dazzled next week – and not just by the sequins on Sienna Miller’s new party dresses.

The department store chain will update the market on Wednesday, providing information on consumer confidence ahead of the critical Christmas period.

A £79 green satin maxi dress designed by British actress Miller has been flying off the shelves since its launch last week.

Her second collection swaps her signature boho chic for party glamor after her first in June saw most pieces sell out within hours.

A greater understanding of rising sales could bring some much-needed joy after Rachel Reeves’ bleak budget heaped more pain and misery on the High Street.

Updates are also expected from online retailer Asos on Tuesday, Primark on Wednesday, Sainsbury’s on Thursday and Asda on Friday.

But retailers are nervous about consumer confidence following the Chancellor’s first Budget.

Interest rates could stay high longer, slowing economic growth and spending. There are also fears that buyers could feel an increase in their employers’ national insurance contributions in their pay packets due to stifled wage growth.

Still, M&S has so far overcome consumer pessimism by investing in its food offering and revamping its fashion lines.

Stocks have been trading at eight-year highs as the recovery gains pace. Stuart Machin, who has continued to implement a plan initiated by chairman and retail veteran Archie Norman, is hoping to surprise the city once again.

After years of M&S’s fashion lines being derided as “disgusting”, partnerships with Miller and Ted Lasso star Hannah Waddingham have brought back the shine.

On the food front, more and more customers are flocking to stores, even for their big weekly shop, bosses have said. Bumper sales mean it is now hot on the heels of Central England rival Waitrose.

But investors have doubts about the future of a partnership with Ocado Retail despite signs of progress.

Aarin Chiekrie, an analyst at brokerage Hargreaves Lansdown, said: ‘Machin has breathed new life into the business. Its food and clothing offerings have been refined, helping it gain market share.’