Environmental campaigners have called for mass direct action against fracking after three of their number were freed by the Court of Appeal on the grounds their custodial sentence had been “excessive”.

The ruling is expected to encourage hundreds of people to join a mass protest against fracking at the Cuadrilla site in Lancashire on Saturday, on the expectation they are now unlikely to be sent to prison even if charged and convicted.

Simon Blevins, 26, a soil scientist from Sheffield; and Richard Roberts, 36, a teacher from London, had been jailed for 16 months, while Rich Loizou, 31, a piano restorer from Devon, was given 15 months in September.

But their sentences were replaced with conditional discharges by three senior judges sitting in London on Wednesday.

The trio were arrested after climbing onto lorries outside Cuadrilla's fracking site in Little Plumpton in a protest which lasted almost 100 hours last July.

The three, who were the first environmental protesters to be imprisoned since 1932, were convicted of public nuisance following a trial at Preston Crown Court.

But quashing their jail terms the Lord Chief Justice Lord Burnett said: "We have concluded that an immediate custodial sentence in the case of these appellants was manifestly excessive.