The firm confirmed his contract had been terminated with “immediate effect”.
Collins kept his head bowed throughout the court appearance, according to Essex Live, during which he admitted to 12 offences included grooming a 14-year-old boy and inciting an underage girl to send him indecent images of herself.
Collins, 52, had sexual online conversations with children and downloaded hundreds of indecent images and videos while living with his parents after a marriage break up.
The ex-Charcol employee, who has an 18-year-old daughter, pled guilty to all 12 charges, which spanned five years and included online communication with a 14-year-old boy in August 2013 about them touching each other, before arranging to meet up for sexual activity.
Collins possessed 886 prohibited or indecent images of children as young as five, including 292 in Category A, the most serious classification for child pornography.
He also held videos showing oral sex and intercourse with dogs, as well as life-threatening acts.
Police searched Collins’ parent’s home on Moran Avenue in Essex on January 20, 2015, after receiving intelligence about his online activity.
Collins admitted everything in a police interview.
He said that all of this started from the breakup of his marriage, after he moved back into his parents’ house and he had more time to look at images on the internet.
Collins, who had no previous convictions, will be sentenced on June 8 at Chelmsford Crown Court.