The retailer introduced the charge in all of its stores with the aim of encouraging customers to reduce the number of bags they use and help the environment.
Other major chains such as Tesco, Asda and Sainsburys have refused to charge for their bags and have claimed that voluntary measures introduced in their stores are helping to reduce plastic bag use.
But Chancellor Alistair Darling announced in this years budget that the Government would introduce legislation to impose a charge on them if it did not see sufficient progress on a voluntary basis by the end of the year.
M&S rolled out bag charges nationwide after a trial period in the south-west of England and Ireland that resulted in a 70% reduction. A spokeswoman said: We have clear evidence that this is working. Since charging was introduced in May, we have seen an 80% reduction in the number of carrier bags used by our customers.
In contrast, Asda has introduced an initiative where plastic bags have been removed from the end of the checkout till and customers have to request a bag from the checkout operator. A spokesman said that it would never charge for its plastic bags and would rather encourage shoppers to change their habits. Asda said that since the initiative started in June its customers had cut their reliance on plastic bags to 40.3% in the south-west.
Image: M&S chief executive Stuart Rose