Jack Bogle says investors need to re-examine their portfolios to make sure they have enough exposure to bonds to protect against what the investment legend calls an “unstable" US government” and a “Brexit debacle”.

Bogle’s comments come as UK Prime Minister Theresa May faces a vote of confidence in her leadership and after MSCI, the world’s biggest provider of investment indices, said British stocks could fall as much as 25% if the country’s politicians reject the UK government’s proposed deal to leave the EU and there is a disorderly exit from the trading bloc.