The Glasgow restaurant, which opened in 2015, will close on 23 March, and is due to reopen on 3 April following a refurbishment as 111 by Modou.
Born in Senegal, Diagne was originally hired by 111 as a kitchen porter before being trained by Simeone on the fundamentals of working in a kitchen and rising through the ranks to become head chef.
He previously played an 'intrinsic role' in the launch of 111's Total Trust tasting menu concept, where dishes are tailor made for individual guests, and also oversaw the recent launch of the restaurant's new 10 course tasting menu.
"This opportunity is completely life changing,” says Diagne.
“Having moved here in 2013, I would never have dreamed that I would be in this position seven years later.
“Nico is like a brother to me. I am more than ready for this next chapter at 111, and I look forward to showing everyone in the industry what myself and my team can do.”
111 by Nico was Simeone’s debut restaurant and provided a test bed for the chef patron’s ‘ever-evolving’ Six by Nico dining concept.
Having opened the first standalone Six by Nico site in Glasgow in 2017, Simeone has since expanded the group at an unprecedented rate, opening locations in Manchester, Liverpool and Belfast in the last year alone.
Six by Nico is due to launch its debut London site (and seventh UK location in total) on Charlotte Street in Fitzrovia at the end of March, with Simeone also potentially eying a further opening in Dublin later this year.
“The time feels right, for both myself and Modou,” says Simeone.
“This has been a personal dream of mine since meeting Modou in 2014, not only getting to know him as a close colleague, but he has become like family to me.
“Six by Nico is going from strength to strength, and as such there are increasing requirements for my energy to continue that development.
“This is Modou’s time to write his own story in the industry, and I will always be there to offer guidance and support when he needs it.
“Modou is ready to begin his next challenge so as one chapter comes to an end for me at 111, another opens for Modou, and I am really excited about it.”