The promotion of Mr Hughes, at present director for engineering, is the result of a decision to split the roles of chairman and chief executive, held until now by Bryan Townsend.
Mr Townsend said that Mr Young, who is 50, had left the company by mutual agreement as there was no longer a role for a full-time managing director.
The changes are thought to be the culmination of a power struggle over the past year. Mr Townsend said: 'We have for some time been considering a redefinition of roles within the company.' He said that he could now concentrate on strategic issues including the shaping of the company's financial and political future.
Mr Townsend said that Mr Hughes, who joined Midlands from the GEC Alsthom power group, had the ideal bakground for the job of chief executive. Analysts say that the appointment reflects Midlands' strategy of diversifying into power generating ventures.
Midlands is a major shareholder in the Enron power station on Teesside, one of the largest independent generating projects in the UK, and is involved in power generation projects overseas. The company also has a joint venture in the UK that will generate electricity from waste.
Mr Townsend said it was vital that the company should expand outside its regulated business of electricity supply and distribution. The aim is to generate at least 20 per cent of group profits from non-regulated activities by the end of the decade.Reuse content