Mustafa Suleyman, co-founder of DeepMind, has quit Google after a seven-year stint in which the pioneering British operation made breakthroughs in AI but struggled to ensure its technology would be used ethically by its giant US owner.

Suleyman was one of three founders of DeepMind, which was set up in the UK in 2010 and was bought by Google in 2014 for $500m. On Thursday, he left the company to become a partner at Silicon Valley venture capital firm Greylock, after a sometimes controversial tenure that included complaints from staff of an aggressive management style.

The DeepMind division sought to operate at arm’s length from its new owner, maintaining a research ethos that insulated it from commercial pressures and attempting to come up with a new governance structure for its powerful AI.