Quintrell, who was formerly operations director at Grass Roots HBI, is now BSI's operations director for meetings and events, the division that was created when the group amalgamated its separate agencies under a single brand this year.
He will oversee BSI's London and Cheadle offices, which provide event solutions, venue-finding and meetings management services.
BSI group managing director Trevor Elswood said: "Jim joins us at a very exciting time, as our meetings and event business grows at a fast pace.
"BSI is already delivering strategic meetings management programmes on behalf of major corporate and public sector organisations, with several new business wins and existing client growth in this area."
Elswood said the growth of the business validated BSI's commitment to transparent business practices, unified business offer, and investment in people and technology.