Being in the middle of the huge change-management programme at the Royal Mail is like being "on an emotional rollercoaster", according to Kevin Green, people and organisational development director at the group.
Royal Mail has seen unprecedented change in the past three years, including the introduction of a single daily delivery, the loss of 30,000 jobs and a complete restructuring of the HR function.
Green, who has been instrumental to many of the changes, said this scale of change means his work has been very rewarding, but also very challenging.
Speaking at the latest Personnel Today HR Directors Club Breakfast Briefing in London, Green said: "It is like being on an emotional rollercoaster to be in the middle of this maelstrom. I have two great days, followed by a dreadful one."
Royal Mail has achieved some successes during its renewal plan, most notably turning a £1m a day loss into expected profit this year of well over £400m. But Green admitted that there is still a long way to go.
"We are talking about an institution that is more than 300 years old: it is not going to take three or five years to change it," he said. "Realistically, it is going to take 20 or 30 years to fully unpick the ways of working that have developed over time."
Green is acutely aware that all these changes will be played out in the full gaze of the public eye.
"Everyone has got a view about Royal Mail - people feel passionately about postmen and post offices," he said.
"And we have to deal with adverse media coverage. We have to chase two or three journalists out of the organisation every week."
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