Unlike the previous arrests, which pertained to the Computer Misuse Act, this one was over blackmail.
The cyber-attack will cost up to £35m, and to make amends, TalkTalk is offering customers a choice of free upgrades.
TalkTalk has issued another statement concerning the recent hack, and initial estimates of the numbers affected were way off.
The Met and NCA have swooped on another teenage boy, carrying out a house search and making an arrest.
Just days after the TalkTalk breach, Vodafone confirms it's suffered an attack too: here's what we know.
ExplainerIf you're on Android, your phone is vulnerable to Stagefright 2.0 – here's everything you need to know.