Emily Thornberry has expressed interest in the idea of four day working weeks but stopped short of backing it to be Labour policy.
Visiting creative organisation 64 Million Artists in the Old Street area, the Islington South MP was not completely won over by the idea, citing the state of the economy as a chief concern.
A pilot scheme began on Monday, June 20, where 70 UK companies and more than 3,300 workers took one day off with no drop in pay. The 4 Day Week campaign is based around the idea that staff get more done in 80 per cent of the time if they are better rested.
"In principle I am supportive of this," said Ms Thornberry - the shadow attorney general. "I think it is important to find that work and private life balance, and it could also be important for mental health reasons.
"My concern is whether it will increase productivity. It has been said it does increase, especially in creative industries. But at a time when we are hitting such a difficult economic period, we are going to end up with high inflation and low wages. There have to be productive gains and look at the evidence."
The pilot scheme is running for six months and a variety of businesses have signed up from fish and chip shops to large corporate firms.
Ms Thornberry met Laura Saxton manager at 64 Million Artists - whose employees are already working four day weeks.
Ms Saxton said: “Our turnover has increased and have not had a situation where we still needed to do work on a Friday.
“It is about putting staff wellbeing at the front of what we do.”
She said that 64 Million Artists, which also gives workers all of August off, has seen a spike in applications since introducing the measures.
The four day working week has not been formally backed by Labour but is an idea the party is considering.
Ms Thornberry added: "There are lots of things that can be attractive about it. But I am concerned about this big anchor [of the financial situation].
"There are two ways of doing this [four day weeks]. There could be companies that want to be attractive to workers and can introduce this. When companies compete for the best people it can help it grow organically. But schools - for example - could not do it without some big changes from the government."
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