Credit Suisse’s incoming chief executive and current boss of Prudential Tidjane Thiam is one of a number of business leaders to have signed a letter endorsing the Conservative Party’s policies, a rare example of a City chief breaking cover and wading into politics.

Thiam, who is chief executive of UK-based insurer Prudential and due to join the Swiss bank at the end of June, is one of 103 business leaders to sign a letter in The Telegraph newspaper today endorsing the Conservative-led Government's business and economic policies.