According to the Guardian Media Group website, viewed by Ethical Consumer in August 2018, the Scott Trust was:
"a private company and the sole shareholder in GMG. It was founded in 1936 as a trust and exists to secure the financial and editorial independence of the Guardian in perpetuity. The shareholders of The Scott Trust take no dividend from the business. All of GMG’s profits are reinvested to support the Trust’s core purpose."
The Scott Trust therefore received a positive Company Ethos mark for having a not-for-profit structure.

Reference:

www.theguardian.com/gmg/ (15 August 2018)