The European Court of Justice said the working day for for those who aren’t based in one place, and move around for their job, should be classed as when they leave home to when they return. The workers were assigned a company vehicle but there was no limited area of operation.

The decision on the case of Spanish security system installation company Tyco Integrated Security SL followed the Advocate General’s opinion on the case earlier this year.

“The journeys of the workers to the customers their employer designates is a necessary means of providing their technical services at the premises of those customers”.

The ruling could also force companies to pay higher salaries to avoid breaking minimum wages laws, as well as giving employees more breaks, lawyers warned.

“The ECJ ruling also underscores the importance of securing the United Kingdom opt-out from elements of the Working Time Directive”.

The ruling could have major implications for some employers. Among the objectives of the ruling is to ensure employees do not work beyond 48 hours a week. However, while the working hours have been defined, there has been no change in the minimum working wage of labourers.

This could be good news if you have to travel to different places every day, and it takes you a significant amount of time.

If they don’t, employees could quickly exceed the number of working hours that they are legally allowed to work and bosses could therefore soon find that they are operating illegally and at risk of facing costly claims against them.

This time has not previously been considered work by many employers. The ruling said: “The fact that the workers begin and finish the journeys at their homes stems directly from the decision of their employer to abolish the regional offices and not from the desire of the workers themselves”.

The Resolution Foundation estimates that as many as 160,000 care workers in Britain are not being paid the minimum wage when travelling between appointments is taken into account.

Journeys made by mobile workers must count as working time, the European Court of Justice (ECJ) has confirmed today.

Anthea McIntyre, a Conservative MEP, said: “This could add significantly to the costs of businesses and interfere with long-established business practices”.

A spokeswoman for the Department for Business, Innovation and Skills said: “We are carefully considering the implications of the judgment”.

Anthea McIntyre, the Tory employment spokesman in the European Parliament, said: ‘This should ring alarm bells.