Bus drivers in Oxfordshire have gone on strike because of a dispute over Christmas pay.
The walk-out on Thursday - with a second strike planned for Monday - comes after talks between Oxford Bus Company and the Unite union broke down.
Company managing director Phil Southall said he was disappointed that a number of their offers had been rejected.
But Unite said the company wanted to "salami slice" the pay of workers "in one of the UK's most expensive cities".
The union said about 450 employees were going on strike, including maintenance staff and admin workers.
The bus operator said it paid drivers premium rates for three bank holidays over the Christmas and New Year period, but the union had asked for five.
It said the extra two days would cost it in excess of £100,000.
Unite said the two bank holidays are legally recognised.
Regional officer Marie Hall said: "This dispute is entirely of the company's own making, as it has totally failed to engage in meaningful negotiations, instead it has adopted an aggressive stance to the workforce in what is a legitimate industrial dispute.
"Because of the hard line tactics of the bosses, our members are reluctantly taking strike action in defence of their incomes in these economically challenging times."
Mr Southall said he was keen to resolve the dispute, but pointed out that more than 50% of services were still running, including full services on its Brookes University and airline routes.
He said: "We have tried to make offers to Unite. We've made them four separate offers to try and compensate our drivers for their strength of feeling… but those offers were rejected without Unite going back to their members."
Contingency timetables are on the company's website.