TWO Merseyside drug barons, who escaped lengthy prison sentences by pretending to be supergrasses, were put back behind bars for even longer yesterday.

John Haase, who got 22 years, and his nephew Paul Bennett, who received 20 years, repeatedly “tipped-off” the authorities about arms stashes across the country.

Their “unique” co-operation finally resulted in rare Royal pardons and early freedom, London’s Southwark Crown Court heard.

Altogether, an “awesome array” of 150 handguns, rifles and machine guns were seized across Britain, along with grenades, masses of ammunition, fake Semtex, drugs and stolen property.

Jurors were told that, although police had increasing doubts about the authenticity of the “finds”, their Customs and Excise “handler” was convinced their assistance was genuine.

So was the judge dealing with them in 1996 for smuggling 60kgs of pure heroin into Britain.

Because of fears they would be assassinated if underworld associates discovered their apparent betrayal, he agreed to “preserve appearances” by openly jailing them for 18 years.

But, shortly after the Liverpool Crown Court case, Judge David Lynch secretly wrote to then Home Secretary Michael Howard.

He recommended the granting of Royal Prerogatives of Mercy and suggested their sentences be slashed to just five years.

Eleven months later – once “time served” had been taken into account – they were released.