McNeill is moving over from Kellogg in Ireland, where he currently holds the position of sales director.
The company said that Adderley had decided that she wanted to re-balance her life and spend more time with her family.
She joined Kellogg’s foodservice business in 2000, moved to the multiples channel in 2001 and was promoted to commercial manager in the multiples channel in 2003.
Prior to Kellogg, she was national accounts controller in the multiples channel for Britvic.
Tony Palmer, Kellogg UK managing director, said: “I and the board are sad to see Alison leave the company, but we respect her decision and I thank her for the contribution she has made over the past five years.
“Jim brings with him a wealth of knowledge, skills and experience both from a sales and Kellogg’s perspective.”