London Underground drivers could take strike action on the day of the royal wedding in a row over pay, union officials have warned.
Aslef said it is considering calling its members out on April 29, which would hit Tube services on the day Prince William marries Kate Middleton.
Drivers went on strike on Boxing Day in the dispute over bank holiday pay, which remains deadlocked.
London Underground took legal action to try to halt the Boxing Day walkout but it failed and the strike went ahead, causing disruption on one of the busiest shopping days of the year.
Aslef is demanding three days’ pay and a day off in lieu for working bank holidays.
London Underground managing director Mike Brown said: “Tube drivers already have very fair levels of pay and get around seven weeks holiday a year, including allowance for bank holidays.
“The Aslef leadership is tearing up long-standing agreements that cover pay and annual leave and demanding even more – triple time and another day off.
“Londoners will simply be stunned at such a claim. The only way to resolve this issue is by getting round the table for constructive talks.
“I urge the Aslef leadership to end pointless strike threats and work with us to resolve this without any disruption to London.”