Legal experts said the decision meant companies which routinely use staff on self-employed contracts – such as taxi or delivery firms – could face potentially huge liabilities if that status is later challenged.

James Williams, the barrister who represented Mr King, said it left employers who have miscategorised workers as self-employed, liable for back holiday pay when the workers’ employment is terminated.

The head of the IWGB trade union, Dr Moyer-Lee, said the “bombshell judgement” was a “game changer for the so-called ‘gig economy'”.

“The law is now recognising the massive unpaid debt of ‘gig economy’ companies to their workers and IWGB members will be coming to collect.”

Jobs of the future may not have stable hours, holiday pay, sick pay, or pensions, the Work and Pensions Secretary has said.

Damian Green described the trend in employment practices towards the so-called “gig economy” as “exciting” and said the changes had “huge potential”.

The Cabinet minister’s endorsement of the approach comes a month after an employment tribunal found that drivers for the Uber car service should in fact get the minimum wage and paid holiday. The tribunal dismissed the taxi company’s claim that its drivers were in fact self–employed and not entitled to these rights.

Mr Green said in a speech at the Reform think-tank on Wednesday morning: “Just a few years ago the idea of a proper job meant a job that brings in a fixed monthly salary, with fixed hours, paid holidays, sick pay, a pension scheme and other contractual benefits.

“But the gig economy has changed all that. We’ve seen the rise of the everyday entrepreneur. People now own their time and control who receives their services and when.

“They can pick and mix their employers, their hours, their offices, their holiday patterns. This is one of the most significant developments in the labour market. The potential is huge and the change is exciting.”

He said the Government had launched the Taylor Review into employment practices to make sure that “employment rights keep up with employment practices”.