Britain’s best-known pollster, head of Mori Sir Bob Worcester, is to step down.

After 36 years he is leaving his post as chairman at the company he founded.

Originally from America, Sir Bob took British citizenship last year.

He is not leaving Mori completely though, as he will chair its new advisory board, become life president and remain the company’s biggest individual shareholder.

It has been a highly successful time in charge – culminating in accurately predicting Labour’s election majority on election night and being knighted in the Queen’s birthday honours list.