Mild dismissal of the idea in Watchtower 1976 8/15:
Are Jehovah’s powerful angels still willing and eager to serve in behalf of his people on earth? Most assuredly! When alerting his disciples to the seriousness of stumbling others, Jesus stressed the concern of the angels in the matter: "See to it that you men do not despise one of these little ones; for I tell you that their angels in heaven always behold the face of my Father who is in heaven." (Matt. 18:10) Jesus’ words do not necessarily mean that each devoted Christian has a special guardian angel assigned to him. But apparently angels are looking out for the spiritual welfare of true Christians as a whole. This is confirmed in question form at Hebrews 1:14: "Are they not all spirits for public service, sent forth to minister for those who are going to inherit salvation?" What marvelous aid is available to us through the angels!