IPSE - is the organistion that represents. They have been consulted by Govt on IR35, won and lost IR35 cases against HMRC and are recognised professional body.

They have just published an article on Gary Lineker hi sIR35 status, social media restraints clients can put on their contractors / employees etc - the article is https://www.ipse.co.uk/ipse-news/ips...-it-means.html