Mahler

Mahler was a servant of the Great Intelligence, who was in a position of authority; answering only to Miss Kizlet.

Before falling under the influence of the Intelligence, Mahler was a working class man. However, following his conversion the Intelligence's influence caused him to affect a more upper class demeanour; wearing glasses and even changing his accent.

When Miss Kizlet was absorbed into the Wi-Fi, the Doctor altered his propensity to obey; causing Mahler to free her.

Soon after, the Intelligence removed its influence from its servants, which freed Mahler's original personality, leaving no memory of how he came to be there. (TV: The Bells of Saint John)