"No. His own company was his employer."
A lot depends on the actual day to day working practices. There are several key elements to take into consideration as far as I'm concerned (and I come across as quite 'difficult' when I 'train' the people I work with to adhere to these principles).
1. Right of Substitution - real or sticky plaster? - Some roles are not subject to simple substitution (requiring bespoke client knowledge as well as security clearances etc.) but should at least be *theoretically* possible.
2. BAU or Project work? If the work can dry up and you are out on your ear, that's a key component of being considered outside IR35 imho. BAU roles are hard to defend as they are typically considered 'employee' type roles.
3. Who do you work for? If you work for yourself, act like it. Clients provide the work, but it's up to you how you do it. If they want you on-site for a meeting, they *ask*, not tell. If they give you a company 'signature' to use, amend it to show you are independent of the client.
Just to re-iterate, above all, if you think you work for yourself, act like it.