The UK's retirement system has become less secure thanks to UK Chancellor George Osborne's "pension freedoms", according to an influential report that argues the move to abolish compulsory annuities entirely was a mistake.

The reforms - which took effect in April 2015 and have caused annuity sales to slump - have left the UK clinging onto a B-grade pension system by a whisker, according to the annual Melbourne Mercer Global Pension Index, which ranks 25 countries' retirement-savings provision according to criteria of adequacy, sustainability and integrity.