For more than a century, Marks & Spencer has been one of the leading high-street stores, but these days it is under attack from all sides, with budget stores selling cheaper clothes, supermarkets upping the quality of their foods and up-to-date fashions available online. On the eve of the company's 2018 report being published, Fiona Phillips speaks to shoppers and former staff to see what can be done to restore the store's fortunes.