According to the report, Barclays, HSBC, Lloyds Banking Group and the Royal Bank of Scotland, the UK's four biggest banks, paid a total of £55.8bn between 2011 and 2015 in conduct and litigation charges. The figure constitutes 9 per cent of the banks' revenues over the period and has represented a 'significant drag on earnings.' Moreover, the banking quartet also reported £20 billion of restructuring charges over the same period, as they continue to reorganise in a bid to simplify their business models.

Additional fines

S&P also predicted that the four banks will face additional charges of £19.5bn over the next two years, representing about 10.5 per cent of their projected revenues. The costs relate to allegations of traders at the leading banks rigging the Libor and £3 trillion-a-day foreign exchange market.

Unpredictable

S&P said in a statement: 'While new conduct issues may emerge, we expect total conduct and litigation charges to gradually subside from 2017, though we acknowledge the timing of such charges is uncertain given the complex nature of legal settlements.'