Court of Appeal judges have rejected the claims of the Staffordshire founder of a paedophile network that his 12-and-a-half year jail term was "manifestly excessive".

The judges, in London, said criminals who engage in the "destructive and perverted activity" of child pornography must expect severe punishment.

Lord Justice Thomas, Mr Justice Saunders and Mr Justice Stadlen sent out a strongly-worded message as they upheld the jail term handed out to Christopher Stubbings, of Crawley Lane, Kings Bromley.

Dismissing his appeal, Lord Justice Thomas said: "In our judgment those who engage in the procurement of child pornography on a significant scale must expect severe punishment.

"It inflicted unimaginable degradation and very serious harm on children in many countries. The depravity it represents is beyond the comprehension of any ordinary person. Such conduct must be deterred and punished."

He said Stubbings was at the centre of procurement of extreme pornography for a period of more than four years. The judge added: "The harm he caused over that period is incalculable."

The minimum term imposed was "entirely merited both to punish him and to deter others from engaging in this destructive and perverted activity".

At Stafford Crown Court in November 2008 Stubbings, then aged 55, was jailed indefinitely for public protection, with a 12-and-a-half year minimum term - the least he must serve behind bars before he can apply for parole.

Lord Justice Thomas said that in 2004 the former management consultant had "founded with others a closely-knit group of paedophiles".

The group had about 50 to 60 active contributors and included members from Europe, Japan and the US.

He said: "The appellant was second in command of this worldwide group and there was clear evidence to show he played a key role in commissioning and procuring hard core paedophilic pornography."