The company Torchbox (creators of Wagtail CMS) are an interesting example of an employee owned company. In their case it was a matter of the founders selling/moving most of their ownership to an Employee Owned Trust (as opposed to starting as a coop from scratch) - EOT is an interesting option in the UK with tax incentives to make it work.
https://torchbox.com/careers/employee-owned-trust
https://baxendaleownership.co.uk/torchbox-digital-agency-mov...
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