Of all the revelations of 2013, perhaps the extraordinary extent of the surveillance state and the shady collaboration between our own spying agencies and those of the US have been the most alarming.

But such connivance is nothing new, as recently declassified CIA documents have revealed. It turns out that British RAF pilots flew illegal spying missions over the Soviet Union in U2 spy planes.

Sixty years ago anti-communist hysteria was increasing in the West. Throughout 1953 then US president Dwight Eisenhower agreed plans to fly illegally over the Soviet Union using the highly advanced and top secret U2 aircraft.

These could fly higher and faster than any Soviet defence system could cope with. Ministry of Defence files on the controversial CIA operations are to this day withheld from the Public Records Office in Kew.

It was generally believed that only US pilots flew the U2s, but investigative journalist Paul Lashmar has published new information in his book Spy Flights of the Cold War.

Lashmar reveals that four RAF pilots, squadron leader Robert Robinson and flight lieutenants Michael Bradley, David Dowling and John MacArthur, were attached to the CIA to fly the missions.

They were even awarded the Air Force Cross for doing so. Each flight made by the RAF men was personally approved by then prime minister Harold Macmillan.

They flew across Soviet territory to photograph rocket sites and other strategic targets.

Robert Robinson, who led the RAF U2 detachment, spoke of his role to Lashmar before his death in 1996.

"In 1958 this was the most secret operation in the world and the British involvement was most secret of all," he said.

Robinson was paid through a secret MI6 bank account. The first missions were flown from Germany in July 1956.

Afterwards security concerns led to further missions being flown from Turkey, Pakistan or Japan.

From the CIA's point of view getting the British involved prepared the way for turning Britain into an extension of US military power.

Washington would extend its nuclear attack aircraft bases in East Anglia in exchange for sharing data collected on the Soviets.

And it would also provide a hostage to fortune if things went wrong. Macmillan agreed the plan and the RAF pilots were sent to Laughlin air force base in Texas for training in 1958. At that time their leader was squadron leader Christopher Walker, but Robinson replaced him when his U2 crashed in Texas, killing him.

Robinson was sent to Incirlik air force base in Turkey in January 1959. This was where CIA Detachment B was headquartered, consisting of four aircraft, seven "civilian" pilots and around 200 support personnel.

The official cover story for the Britons was that they were temporary employees of the Meteorological Office.

Over Russia, Robinson recalled, the U2's ability to fly so high protected it from Soviet aircraft.

"You were always looking behind and you would see many, many aircraft all lined up below you but with the inability to reach you," he remembered.

It wasn't until 1995 that the CIA declassified the number of U2 overflights of the Soviet Union, which was 24.

And until this year the number of overflights flown by British pilots remained secret.

But the project was, of course, headline news in 1960 when the plane's invulnerability was finally breached. An aircraft flown by Gary Powers was shot down over Sverdlovsk with a SAM-2 missile on May Day.

Observers on Red Square for the annual parade noticed a military officer approaching Soviet leader Nikita Khrushchev, whose cry of "well done!" was overheard by onlookers.

But uncertainty over what exactly had happened continued for three days, after which the news that Powers had been captured alive caused the British to pack up and get out of Turkey in a hurry.

They had to leave to avoid embarrassing the Turkish government, which didn't know they were there.

The Snowden revelations about the extent of NSA and GCHQ collaboration in spying, phone-tapping and communications interception is merely the latest example of a sordid history of abuse of power at the heart of anti-communist regimes.

Marx did warn that history repeats itself. Perhaps Chancellor Angela Merkel should not be surprised that her phone was tapped.