THIS wasn’t just a picket line, it was a Marks & Spencer picket line.

Members of the store’s staff union GMB rallied yesterday outside the London headquarters of the retail giant over “unethical and unlawful” employment practices.

M&S uses a complex system of subcontracting to employ hundreds of workers at its distribution depot near Swindon. Some agency workers are paid minimum wage whereas directly employed staff get £2 more per hour for the same work, according to the GMB.

Many agency staff have worked on the site for several years but are guaranteed only 7 hours per week.

Yesterday’s protest at at Paddington was the third on the issue.

GMB says the two-tier pay system is illegal, breaching the Agency Worker Regulations, which came into effect in 2011, guaranteeing equal pay for agency workers after 12 weeks.

GMB regional organiser Carole Vallelly said: “GMB consider that this is unethical and unlawful” and added that M&S was breaking its own code of ethics on treatment of staff.

Protesters also slammed the company’s use of minimal hours contracts.

“GMB is pressing M&S to investigate the working practices at the South Marsden site. At Swindon mothers on the bus on their way into work, having left their children with child-minders, get text messages saying they are not needed that day,” Ms Vallelly said.

Former M&S boss Lord Rose has been put in charge of the Remain campaign, pressing for Britain to stay in the European Union.

“The Remain campaign made it very clear that they don’t intend to place a very high priority on employment rights in the forthcoming EU referendum,” said GMB.

Marks & Spencer was keen to pass the buck to its subcontractor yesterday. A spokesman said: “Our site in Swindon is operated by our logistics partner DHL. All employees are employed either directly or indirectly by DHL.”