More than 200 UK outlets of Karen Millen and Coast are to close, putting up to 1,100 jobs at risk, after the fashion brands’ online business was bought out of administration by internet retailer Boohoo for £18m.

Administrators at Deloitte said 62 head office staff had been made redundant with immediate effect and stores would only stay open for “a short time” while stock was sold off.

The two chains currently trade from 32 standalone stores and 177 concessions in department stores including Debenhams and House of Fraser in the UK.

Like many other retailers, the fashion chains have suffered from higher costs and falling shopper numbers on the high street amid weak consumer confidence and changing shopping habits.

Other fashion chains to have collapsed this year include Jack Wills, LK Bennett, Pretty Green and Select. Others have been forced to seek rent cuts to survive, including Philip Green’s Topshop group Arcadia, Debenhams and Monsoon.

Rob Harding, joint administrator at Deloitte, said: “As we continue to see, the retail trading environment in the UK remains extremely challenging.” He said Karen Millen had tried and failed to find a buyer for the whole business, but the deal with Boohoo would enable “the survival of these iconic British brands through an online platform”.

Boohoo said the two brands had online sales from their own websites of just over £28m and would be “highly complementary additions” to its portfolio of brands, which already includes PrettyLittleThing, Nasty Gal and MissPap.

John Lyttle, the group chief executive of Boohoo, said the acquisition was “another milestone in the group’s growth story as it continues to invest in its scalable multi-brand platform and gain further share in the global fashion e-commerce market”.

Analysts said the acquisitions would help Boohoo, which focuses on young fashion, shift towards a more grown-up market as its shoppers got older and shied away from disposable fashion.

Kevin Stanford, who co-founded the group with his former wife Karen Millen in 1981 before the pair sold the business to Icelandic investment firm Baugur in 2004, said he thought Boohoo would make a better job of looking after the brand than its current owner, the Icelandic bank Kaupthing.

“Its really sad for all the people working there but something had to happen as the current owners have sadly destroyed the brand … That’s what happens when banks run fashion companies.”

Quick guide Why are UK high street retailers in trouble? Show Hide What’s the problem? Physical retailers have been hit by a combination of changing habits, rising costs and broader economic problems as well as unseasonable weather. In the past few years names such as Mothercare, Karen Millen, Toys R Us, Maplin and Poundworld have disappeared from the UK high street as a result. In terms of habits, shoppers are switching to buying online. Companies such as Amazon have an unfair advantage because they have a lower business rate bill, which holds down costs and enables online retailers to woo shoppers with low prices. Business rates are taxes, based on the value of commercial property, that are imposed on traditional retailers with physical stores. At the same time, there is a move away from buying "stuff" as more people live in smaller homes and rent rather than buy. Uncertainty about the economy has also slowed the housing market and linked makeovers of homes. Those pressures have come just as rising labour and product costs, partly fuelled by Brexit, have coincided with economic and political uncertainty that has dampened consumer confidence. What help do retailers need? Retailers with a high street presence want the government to change business rates to even up the tax burden with online players and to adapt more quickly to the rapidly changing market. They also want more political certainty as the potential for a no-deal Brexit means some are not only incurring additional costs for stockpiling goods but are unsure about the impact of tariffs at the end of this year. Retailers also want more investment in town centres to help them adapt to changing trends, as well as a cut to high parking charges, which they say put off shoppers. What is the government doing? In the December 2019 Queen's speech, the government announced plans for further reform of business rates including more frequent revaluations and increasing the discount for small retailers, pubs, cinemas and music venues to 50% from one-third. It has also set up a £675m "future high streets fund" under which local councils can bid for up to £25m towards regeneration projects such as refurbishing local historic buildings and improving transport links. The fund will also pay for the creation of a high street taskforce to provide expertise and hands-on support to local areas. What is the outlook in 2020? Some retailers could go under. Weakened by a difficult Christmas – which accounts for the entire annual profits of many retailers, and with further potential Brexit wobbles to come – retailers are facing another tough year in 2020. The latest rise in the national minimum wage in April will also add to costs and hit profits. On the plus side, there are hopes of a boost to the housing market from increased certainty about Brexit after the general election. There are also signs that the shift to online shopping is slowing, potentially easing the pressure on high streets. Sarah Butler Photograph: Matthew Horwood/Getty Images Europe

Millen added: “I feel a great sense of loss that a brand that became iconic on the high street and across the world is now likely to close its doors and put an end to everything we put our heart and soul into. I feel sad for everyone who stands to lose their jobs . It’s the end of an era. It’s a very, very sad day.”

Karen Millen and Coast together employ about 1,100 people across the UK, none of whom have been taken on by Boohoo under the deal.

Both brands also have outlets overseas. Coast has concessions in the Middle East and outposts in Singapore and Malaysia. Karen Millen has three flagship stores in the US – in New York, Chicago and Santa Monica – and others in Australia as well as concessions and franchise stores in 63 other countries. Deloitte said the overseas businesses would continue trading “in the short term”, suggesting that these stores would also close in coming months.

The Karen Millen holding company lost £5.7m in the year ending February 2018, after losing £11.9m in the previous financial year. The two brands had combined sales of £174m in the year to February 2019.

Deloitte was hired as adviser about six weeks ago to assess options, and quickly decided a sale was the best option.

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A large number of Coast’s concessions are inside Debenhams and House of Fraser department stores, which are being forced to close branches to weather the high street trading crisis. Coast was owed £1m when House of Fraser went into administration a year ago and closed more than 20 stores in a prepack administration deal in October 2018 when it was acquired by sister company Karen Millen.

Both brands have endured a rocky history since being bought by Baugur which collapsed in 2009. They have since been controlled by failed Icelandic bank Kaupthing.

Boohoo has been one of the few retailers to buck the trend of painful decline in the sector. In June, the company reported a 39% sales rise in the three months to 31 May.

It was founded by the fashion entrepreneur Mahmud Kamani and Carol Kane in Manchester in 2006. It floated on the stock market in 2014 and its value has since soared. Its shares climbed 4% after the Karen Millen deal was unveiled, valuing the business at £2.8bn.