Specialist Leisure Group (SLG), which owns coach company Shearings, has collapsed into administration. Travel trade organisation Abta said more than 64,000 bookings have been cancelled and more than 2,500 jobs lost.
It added that the vast majority were coach package holidays which are financially protected so customers with these bookings will receive a full refund.
Abta believes the coronavirus pandemic was the main reason for SLG's financial difficulties, as it struggled to provide thousands of refunds for cancelled trips while new bookings had ground to a halt.
John de Vial, Abta's director of membership and financial services, said: "The Specialist Leisure Group included two of the UK's best known coach holiday brands, Shearings and