Two of the group companies, Shearings and Wallace Arnold, were members of Abta, while National Holidays and UK Breakaways were members of the Confederation of Passenger Transport.
The group had more than 64,000 bookings, the vast majority of which were coach package holidays. All package holiday bookings are financially protected so customers with these bookings will receive a full refund, with coach packages protected by the Confederation of Passenger Transport.
Shearings also offered a small number of flight package holidays, which are Atol protected and will be processed by the CAA.
Shearings had been providing holidays to the UK public for more than 100 years with its roots traced back to 1903.
The impact of the Covid-19 pandemic is believed to be the main reason behind the collapse of the group, as it struggled to provide thousands of refunds for cancelled holidays while new bookings ground to a halt.
The group contained five companies in total that sold holidays and other travel arrangements:
Shearings Holidays Limited
Wallace Arnold Travel Limited
National Holidays Ltd trading as Caledonian Travel and Travel Style
UK Breakaways Limited
Shearings Hotels Ltd trading as Bay Hotels and Coach and Country Hotels
John de Vial Abta director of membership and financial services, said: "The Specialist Leisure Group included two of the UK’s best known coach holiday brands, Shearings and National Holidays, two much loved holiday companies who for many years have provided holidays both at home and overseas to a very loyal group of customers.
"Today is a very sad day for these customers and the thousands of staff who will have lost their jobs.
"The fact that two such well-known brands with a loyal customer base have had to call in administrators is a stark indication of the pressure that the holiday industry is under as a result of the coronavirus pandemic.
"Abta has repeatedly highlighted to the government the urgency of the situation and the need to set out a coordinated strategy with clearer communication if it wants to help avoid significant job losses and support companies to weather the storm."
The CAA confirmed Shearings had a small number of consumers with flight-inclusive packages, which will be Atol protected. For those bookings, it will be contacting consumers directly or via their agent to provide guidance and support.
CPT chief executive Graham Vidler added: "This is a sad day for all those involved with Shearings and the wider coach tourism industry, our immediate thoughts are with those employees who now face an uncertain future.
"Today’s events show the need for the Government to urgently step in and provide support to the wider coach tourism industry, during the Covid-19 pandemic, which has been lacking to date.
"Customers who have booked coach package tours with Shearings are protected by the Government-approved consumer protection scheme Bonded Coach Holidays (BCH). They will be contacted by the administrator who will inform them of how to make a claim.
"All coach operators providing coach package tours must have full consumer protection in place to comply with The Package Travel and Linked Travel Regulations 2018, which means that customers can have confidence that their money is safe."