Retiring Telstra chief executive Andy Penn will leave a legacy of transformation that will be further enhanced if his successor, Vicki Brady, can capitalise on years of restructuring and lead the nation’s largest telco back to sustained growth.

Penn took over the $46 billion company in May 2015 at a difficult time, with earnings plunging $600 million that year. The toll of the National Broadband Network on Telstra’s fixed line business was becoming clearer, mobile markets faced intense competition, and investors were fretting about the group’s prized dividend.