Wrong
"The United Kingdom has raised no objection to the release of Leo Sayer from the bonds of British citizenship.."
UK Law:
"You will not normally lose your British nationality if you become a citizen or national of another country. If you are a British subject otherwise than by connection with the Republic of Ireland you will lose that status on acquiring any other nationality or citizenship. If you are a British protected person you will lose that status on acquiring any other nationality or citizenship."
Australian Law:
"Under present legislation the United Kingdom recognises dual nationality, and, if you acquire Australian citizenship, this does not affect your right to hold a British passport and live in the United Kingdom."