In times past, when Amazon offered you Free Super Saver Delivery, it really meant free. That all changed in July 2013, when the company introduced a £10 minimum spend to have your order delivered on the house. Almost two years later, the online retailer has announced it's raising that limit again, by doubling it to £20. One reason for the change could be to incentivise customers to put down £79 for Prime, which ships millions of items next day (and includes video streaming and other media services). The company may also be moving to to cover the cost of its wide range of delivery options, which now include same-day collection and shipment to your local Post Office. Regardless, the new threshold will come into effect from 6pm tonight (UK time), so if you have some low-cost items sitting in your basket, now might be the time to buy them.