St John Ambulance made 155 redundancies in 2012 from a workforce of just under 2,000, the charity has said.
The reduction in staff numbers was part of a major reorganisation in which the first-aid charity moved from 41 semi-autonomous divisions to eight regions, which it said would be cheaper and would allow better sharing of resources.
According to its annual report and accounts, filed last week, the charity reported an operating deficit of £9.5m on income of £90.6m. This included £2.1m on transferring assets to new "commanderies" – new independent charities in the Channel Islands and the Isle of Man that are no longer part of the main organisation.
The charity has reported a deficit in each of the past five years, but still retains unrestricted funds of £113.5m.
Steve Foster, director of human resources at St John Ambulance, said the previous structure did not allow the charity to achieve its objectives as it wanted.
"The new changes mean an increased focus on our charitable impact," he said. "The new structure is less expensive and means that resources can be shared so we can better target areas that need our help."
Accounts show the charity’s highest-paid member of staff earned between £140,000 and £150,000.