He is president of the Society of Maritime Industries (SMI), and vice-president and treasurer of the Institution of Mechanical Engineers in Great Britain.
Bethel entered the oil industry, joining Vetco Gray in Aberdeen before being transferred to Houston, Texas in the United States to become a design engineer.
In 1991, Bethel was appointed chief executive of the Lanarkshire Development Agency, part of the Scottish Enterprise network, a position he held until April 1996.
After leaving Motherwell Bridge in January 2004, Bethel became Chief Executive of Babcock Marine, which, with over 8,000 employees at the time, was the largest provider of engineering services to the Royal Navy.
[citation needed] During his time at Babcock Marine, Bethel oversaw the building of two Queen Elizabeth-class aircraft carriers, despite cutbacks that were announced in the 2010 Strategic Defence and Security Review.