City minister John Glen has blasted the "maverick figures" leading Labour as the party continues its charm offensive throughout the Square Mile.

Speaking towards the end of his first six months in the job, Glen told senior figures from the financial services sector that "it is not Brexit that poses the greatest risk to the health" of the City, but rather Labour "which would unravel decades of economic progress".

It is "a party led by maverick figures who now find themselves at centre stage in our political life", Glen told delegates at TheCityUK's annual conference, reminding them that shadow chancellor John McDonnell – who is due to speak later today – has hailed Marxism and said it was his job to overthrow capitalism.

"I dont believe that this is a man ready to occupy 11 Downing Street," Glen said. .

"To counter this threat to our economy, we must redouble our efforts in office to ensure we are building an inclusive and responsible brand of capitalism."

The minister also teed up his boss Philip Hammond's Mansion House speech next week, which is widely expected to set out his vision for an evolution of the free market economy, emphasising that the "free market and financial services create wealth and support our liberal democracy".

Conservatives are increasingly under pressure as Labour has been making inroads into the City. McDonnell and members of his team including Glen's opposite number Jonathan Reynolds have been meeting with a number of banks and other businesses as they seek to put the "threat" rhetoric of last year behind them.