In somebody’s train
Definition 1 of 1
Pro Tip 1/3Historical Usage
The phrase is mostly used in historical contexts or literature, referring to times when royal processions were common. 
The knights rode in the prince's train, a display of loyalty and grandeur.
Pro Tip 2/3Figurative Meaning
It can be used metaphorically to imply someone is significantly influenced by another's ideas or movement. 
As a dedicated follower, he was always found metaphorically in his leader's train.
Pro Tip 3/3Not Physical
The phrase does not necessarily mean physically following; it often refers to support or allegiance. 
Many intellectuals were in the philosopher's train, spreading his teachings.