London's Boxing Day shoppers and tourists carried on regardless despite a "completely unnecessary" Tube strike disrupting large parts of the service.
Aslef, the train drivers' union, took the action in a long-running row over bank holiday pay.
The disruption, which has already led to the Premier League derby between Arsenal and West Ham United being postponed, will continue with two further walkouts on the last two Fridays in January.
Drivers are paid about £46,000 per year but want more money for what they say is an increased bank holiday workload - but bosses at Transport for London say their pay deals take that into account.
Some shoppers took to Twitter to voice their annoyance at the delays.
As millions of bargain hunters buzzed through the capital, the Tube network continued to run but with a limited service.
Howard Collins, LU's chief operating officer, said: "Services on the Bakerloo, Central and Victoria lines are running to central London this morning serving the West End and busy shopping areas in west and east London, with very limited services on all other lines.
"The bus network is also in full operation serving all main shopping centres and sporting events.
"Tube services will be busy and we would urge customers to check on the TfL website and TV and radio bulletins before setting off.
"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.
"In doing so they have demonstrated a complete disregard for our customers and for the thousands of transport staff who will be working hard to get around the capital."
The union said in a statement before the strike that 90% of members were in favour. "We want a volunteer service on Boxing Day with those working getting more than flat time. An enhancement for this day will ensure members will be able to swap duties with someone who wishes to work.
"We don’t expect support or gratitude from the public who will be inconvenienced on 26 December. But we hope there will be understanding."