Halpin indicated that change is on the way for the five-year-old magazine, citing the title's Red Hot entertainment section, which was this year scrapped and replaced with one called Talk. 'We threw it out and started again,' she said.
The appointment of Harper, who has been features editor for a year, ends a lengthy search to fill the deputy editor berth. Previous incumbent Hero Brown left in August 2002.
Harper will continue to control features on the Hachette Filipacchi UK title, with Amanda Morrison covering lifestyle content. This includes beauty, home, food, garden and travel. Morrison is standing in for assistant editor Andrea Childs, who is expected back from maternity leave in August.
Halpin, who joined the title four years ago, has been editor for the last two years.
She said: 'Features are more and more important in Red. We do lifestyle well, but I want to see things like health as part of the main features in the magazine.
'For the Red reader, it is a huge issue and we are always looking for good hooks and news angles. Any lifestyle research in the thirtysomething age group is also helpful, including themes like stress, tiredness and free time,' she added.
Red launched in February 1998, targeting what it called the 'middle youth' market, although Halpin is keen to see the phrase quietly buried.
'We have put that to one side. We now have a broader audience and there is no need for narrow labels,' she said.
Harper started as a features writer at the Daily Express in 1993, moving to the Mail on Sunday before going freelance, where she worked for the London Evening Standard and Elle.
Meanwhile, Paul Browning is set to join Red from Front magazine in May, as senior designer.