In a surprise announcement, Stagecoach UK Bus MD Robert Montgomery, 65, leaves the Group next month after 15 years with the business.
The timing and tone of the statement from Stagecoach has prompted speculation that he may have a new post with another organisation.
Mark Threapleton, 62, currently Stagecoach London MD, becomes UK Bus England and Wales MD.
Robert Andrew, 53, currently Regional Director for Scotland, becomes Scotland MD.
Both report directly to Group CEO, Martin Griffiths.
In a statement Mr Montgomery says: “It has been a privilege, a challenge and enormous fun working for Stagecoach for the last 15 years.
“I've worked alongside a host of talented and committed people, delivering good quality bus services in a dynamic commercial environment.
“I wish Stagecoach well and also look forward to new adventures elsewhere.”
Mr Montgomery joined Stagecoach in 2002 as UK Bus Service Development Director. He was appointed Deputy MD in May 2012 and, subsequently, MD in May 2013.
Since 2013, he has helped deliver the Group’s wider strategy on harnessing digital technology, as well as continuing the company’s track record of innovation with the launch of new urban express and high frequency minibus services.
He has also overseen the development of new talent through the Stagecoach UK Bus graduate recruitment programme.
Paying tribute, Mr Griffiths, said: “I'd like to thank Bob for the contribution he has made to the business.
“We have led the sector in delivering new digital tools for our customers, from smart ticketing and contactless travel to a new website and smartphone app, as well as offering the best value bus travel in Britain.
“This means our buses are well positioned to help government address the challenges of increasing road congestion and worsening air quality caused by too many cars in our towns and cities."
Welcoming the new appointments, Mr Griffiths added: “We have a talented team of experienced and very capable managers across the Group. These changes will ensure we continue to be well placed to manage the changing environment for public transport, and deliver on our programme of investment in improvements for our customers and our people.
“Mark has over 40 years' experience in the public transport sector and is one of the most respected managers in the industry. Most recently, he has been responsible for the very successful management of the Group's London bus business and building a strong working relationship with Transport for London. Mark was previously the Managing Director of the Group's largest regional bus business in Manchester, overseeing a period of consistently strong growth.
“Robert Andrew is part of the senior leadership team. He brings over 30 years' experience to the role, including extensive engagement with stakeholders across Scotland. Robert has held a number of senior positions across our UK Bus businesses and is well placed to address the issues and opportunities in the Scottish bus industry."