Husnain Rashid, 32, of Leonard Street, Nelson used a chat group to encourage supporters to target the young prince, posting the address of his school with the chilling message “even the Royal family will not be left alone”.

was handed a life sentence with a minimum term of 25 years at Woolwich Crown Court in July last year after pleading guilty to four terror offences.

But his tariff was reduced to 19 years by the Court of Appeal on Tuesday.

Lord Justice Holroyde, sitting with two other senior judges, upheld Rashid’s life sentence, rejecting an argument by his lawyers that it was not justified.

He told the court: “We are satisfied that (the Crown Court judge) was entitled to come to the conclusion that the seriousness of these offences, taken together, was such as to justify a sentence of life imprisonment.”

However, he said the original minimum term was too long, adding: “We accept that the judge fell into error in some aspects of his application of the sentencing guidelines.”

The court heard police found nearly 300,000 messages on Rashid’s mobile phone, and further evidence on his computer, when he was arrested in November 2017.

He also posted suggestions of which British football stadiums terrorists could strike following the deadly attack outside Besiktas’s ground in Turkey.

His list of targets for “lone wolf” attacks, involving vehicles, weapons and bombs, were wide-ranging and included British Army bases, shopping centres and Government buildings.

He also suggested supporters should target high-profile events including the 2018 football World Cup in Russia and the New York Halloween parade.

Rashid initially maintained his innocence, but changed his pleas to guilty after the prosecution outlined its case at trial.

He admitted three counts of engaging in conduct in preparation of terrorist acts and one count of encouraging terrorism.

Two further charges of dissemination of a terrorist publication were laid on file.