Politicians' voice: sound of PMs Thatcher and Blair
Margaret Thatcher and Tony Blair had voice coaching which may have helped them rise to the top, but not all politicians have been able to command such respect with their voices.
Adam Fleming looked into the archives to see how politicians changed their tune.
The film was followed by a debate with voice coach Barbara Berkery and the broadcaster and peer Joan Bakewell on accents of those in the public eye.
More clips and news on our BBC website, external; 'like' us on Facebook , externalpage; follow us on Twitter, external