Definition of backroom boy in English English dictionary
Someone who has an anonymous support role in an organization, especially a technician or scientist; a boffin
an expert adviser involved in making important decisions but usually lacking official status
You can refer to a man as a backroom boy when he does important work in an organization and has good ideas but is not seen or known about by the public. someone such as an engineer or scientist whose work is important but who does not get much attention or fame