The same situation is here. Gillingham is a character who appears in the novel very rarely. He is Mr. Phillotson’s best friend since they were kids. Like some other characters like Phillotson and Sue, he also works as a teacher in Shaston. He doesn’t have a big impact and a big role in the dynamics of the book. We can say that even having small amount of lines he is kind, good, open-minded, hard-working character with nice dreams and desires.
Gillingham in the Essays