He acquired a fearsome reputation for his “dirty tricks” to keep Richard Nixon in power during the Watergate years, but later found Christ and committed his life to sharing the Christian faith with prison inmates.

Chuck Colson, who died on Saturday aged 80, served as Nixon’s special counsel from 1969 to 1974 during which time he shamelessly worked to discredit politicians, journalists and activists opposed to the President – names down on his self-compiled “enemies list”.

He even boasted that he would “walk over my own grandmother” to secure Nixon’s re-election.

But he would eventually go to jail in 1974 for his illegal activities in office. Although he was not directly involved in the Watergate scandal, he pleaded guilty to obstructing justice because of his involvement in earlier attempts to discredit former Pentagon official Daniel Ellsberg, who was suspected of leaking a top-secret document on the Vietnam War to the New York Times and The Washington Post.

As his political career hit meltdown, Colson had a profound religious transformation. Going against the advice of his lawyers, he pleaded guilty to obstruction of justice because he saw it as the price to pay for his old life and a way “to be free to live the new”.

He emerged from prison in 1975 a changed man and went on to become a leading spokesman for evangelicals in the US, featuring in Time magazine’s “25 Most Influential Evangelicals in America” list in 2005.

In 1976, Colson founded Prison Fellowship Ministries to advocate for prison reform and help prisoners turn their lives around.

In 1993, he won the Templeton Prize for his work in advancing the cause of religion.

Evangelist Billy Graham paid tribute in a statement: “For more than 5 years, Chuck Colson, a former prisoner himself, has had a tremendous ministry reaching into prisons and jails with the saving Gospel of Jesus Christ.

“When I get to Heaven and see Chuck again, I believe I will also see many, many people there whose lives have been transformed because of the message he shared with them.

“He will be greatly missed by many, including me. I count it a privilege to have called him friend.”

Lee Strobel, author and Christian apologist, said: "I'm saddened by Chuck Colson's passing yet rejoicing that he is now in the presence of the Lord he loves so much."

Apologist Ravi Zacharias said in a statement: "His courage to share the Gospel with clarity and his deep concern for our deteriorating society were ever at the heart of his thinking. Truly, Chuck was a bold witness for our Lord."