Nancy Cruickshank has unexpectedly left Hearst Digital, the National Magazine Company division, after a year as managing director.
The company has promoted Alex Ballantyne, managing director of its site NetDoctor.co.uk, to replace her.
Ms Cruickshank joined Hearst Digital, which publishes cosmopolitan.co.uk, goodhousekeeping.co.uk and allaboutyou.com, after it bought Handbag.com in October 2006.
Within weeks, she had been promoted to managing director of the division.
Previously Ms Cruickshank spent six years running Handbag.com, which NatMags bought from Sir David and Sir Frederick Barclay for a sum sources put at £22m.
"We always knew that Nancy would want to move on in due course having spent six years at Handbag prior to our acquisition. We are very grateful for the work she has done over the last year and wish her the best in her next role," said Duncan Edwards, chief executive of the National Magazine Company.
NatMags recently announced that its digital business would focus on fewer sites with the potential to grow significantly.
"I am delighted that Alex has accepted our invitation to lead NatMag's digital publishing business," Mr Edwards added.
"The business has been a focus for significant investment activity over the last year and we look forward to seeing these dynamic ventures continue to grow under his leadership."
When NatMags bought Handbag.com, one of the UK's biggest women's websites, a year ago, it was expected that it would spearhead a major expansion into the US backed by the resources of NatMags' parent, the Hearst Corporation. Ms Cruickshank was expected to play a key role in that expansion.
The sale of Handbag.com to NatMags represented a windfall for Sir David and Sir Frederick Barclay's Press Holdings, which owned 50% of the website and bought out the retailer Boots's 50% share for about £500,000 in March 2005.
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