Blackmail, defined under Section 21 of the Theft Act 1968, involves making unwarranted demands with menaces to gain personally or cause loss to another. Conviction for this offence can lead to a maximum sentence of 14 years imprisonment.
For example, Grant Derek Giblin was arrested after an investigation found he had been using apps to contact children, aged between 10 and 16, and befriend them to gain trust and encourage them to send images of themselves. Once he had received these, Giblin would blackmail his victims into performing sexual acts on themselves before again sending the content to him.
But the case involving sick Northern Ireland man Alexander McCartney was one of the most shocking cases yet, where he pretended to be a teenage girl to befriend, then abuse and blackmail children around the world, often sharing images with other paedophiles.
Some of the children were as young as four. Some had never told anyone what they had been through - until police knocked on their door. McCartney gradually admitted 185 charges including manslaughter after a 12-year-old girl he was abusing took her own life. He has been jailed for a minimum of 20 years.
Here are some of the most notable blackmail cases that have resulted in prison sentences.

1. Grant Derek Giblin
National Crime Agency officers arrested Grant Derek Giblin after an investigation found he had been using social media apps to contact children between November 2021 and August 2023. Giblin would target the children, aged between ten and 16, and befriend them to gain their trust and encourage them to send him images of themselves. Once he had received these, Giblin would blackmail his victims into performing sexual acts on themselves before again sending the content to him. He was sentenced to eight and has an extended licence period of a further eight years, be subject of an indefinite Sexual Harm Prevention Order and be on the sex offenders register for life. | National Crime Agency

2. Alexander McCartney
Prolific online predator Alexander McCartney from Northern Ireland pretended to be a teenage girl to befriend, then abuse and blackmail children around the world, often sharing images with other paedophiles. Some of the children were as young as four. Some had never told anyone what they had been through - until police knocked on their door. McCartney gradually admitted 185 charges including manslaughter after a 12-year-old girl he was abusing took her own life. He has been jailed for a minimum of 20 years. | PSNI Photo: PSNI

3. Brandon Woolveridge
A man released early from prison under the government’s overcrowding scheme was jailed again for blackmailing one of his previous victims within two weeks of his release. Brandon Woolveridge, 25, had served part of a 42-month sentence for blackmailing people over their missing pets. After being freed in mid-September, Woolveridge was arrested on September 24 for demanding £1,000 for the return of a missing dog, using the same tactics as before. He was sentenced to an additional 27 months at Preston Crown Court, with Judge Heather Lloyd condemning his "identical modus operandi." | Cumbria Police Photo: Cumbria Police

4. Jordan Guest
A widower from Warrington was scammed out of £20,000 by a manipulative blackmailer after joining Tinder, believing it was an age-verified platform. The man was tricked into chatting with "Georgia," who he thought was at least 18 but later discovered was posing as a 15-year-old. After he ended their chats, he was contacted by a man claiming to be part of a paedophile hunting group, who blackmailed him for five months, demanding £20,000 and attempting to extort an additional £13,000. The blackmailer, Jordan Guest, was revealed to have posed as both "Georgia" and "John" to exploit the grieving man. Guest was sentenced to 28 months in prison for his "sophisticated and manipulative" scheme. | Merseyside Police