Strike action heavily disrupted London's Underground train network on Wednesday, as hundreds of thousands of bargain hunters headed to the shops for the traditional Boxing Day sales.
All 13 of the Tube lines were running a reduced service after just a third of drivers turned up for work in a dispute between the Aslef union and the network operators over payments for working on national holidays.
Howard Collins, London Underground's chief operating officer, said: "This strike action is completely unnecessary.
"Train drivers are paid a salary that reflects some bank holiday working, but the Aslef leadership is demanding to be paid twice for the same work and has rejected our attempts to resolve the matter."
Despite the transport problems, shoppers formed long queues from the early hours of the morning outside London's top department stores including Harrods and Selfridges.
Many of the bargain hunters were Chinese, with Harrods creating a separate queue outside its store in the upmarket district of Knightsbridge for those looking for reductions on designer goods such as Gucci.
Sue West, director of operations at Selfridges, said handbags and menswear were particularly popular items in the sale at its flagship branch on London's main shopping thoroughfare of Oxford Street.
She said: "Of the people queuing to get inside 60 percent or 70 percent were men. It's a great day for men's shopping. It's a tradition and people want to experience it.
"Online sales for us have been great, but year on year people still want to experience the Boxing Day sales."
British retailers slash prices on the day after Christmas Day, with big-ticket items such as TVs and computers carrying the biggest reductions.
The price comparison site MoneySupermarket.com estimates that shoppers in Britain will spend £2.9-billion in the sales.
The British Retail Consortium had described high-street spending as "acceptable but not exceptional" during the Christmas period.