Grieving fans on Monday mourned the death of George Michael as British charities revealed that the pop star had secretly been a major behind-the-scenes donor who gave his time and money to support cherished causes.

The man with the reputation for self-indulgence had actually given millions of pounds (dollars) to charities involved with helping children, cancer victims and AIDS sufferers.

He was also remembered for small acts of kindness: helping his village in north London get a Christmas tree, and volunteering at a homeless shelter.

Former Beatle Paul McCartney posted a statement on his website praising Michael's "sweet soul music," which he said will live on.

A George Michael fan reacts outside Michael's London home, Monday Dec. 26, 2016. George Michael, the British pop superstar who reached early fame with WHAM! and went on to a solo career lined with controversies and chart-topping hits that blended soul and dance music with daring social and personal commentary, has died, his publicist said Sunday. He was 53. (Stefan Rousseau/PA via AP)

"Having worked with him on a number of occasions his great talent always shone through and his self-deprecating sense of humor made the experience even more pleasurable," McCartney said, posting a picture of the two of them together.

The singer's death was announced late Sunday. Many paid tribute on Facebook and Twitter and others cited years of good works that received little publicity — largely because Michael insisted on keeping his charity work out of the limelight.

Fans placed flowers and other tributes at his homes in north London and in Goring, England, where he died of apparent heart failure.

Michael's later years were marked by occasional brushes with the law and a series of driving incidents related to substance abuse, but this was overlooked Monday as directors of major charities and advocacy groups stepped forward to praise him.

Among the groups he supported were the Terrence Higgins Trust, which helps people with AIDS, Macmillan Cancer Support, and Childline, which offers confidential phone counseling for young people.

Childline founder Esther Rantzen said Michael gave royalties from his 1996 hit "Jesus To A Child" to the charity along with many other donations.

"Over the years he gave us millions and we were planning next year, as part of our 30th anniversary celebrations to create, we hoped, a big concert in tribute to him — to his artistry, to his wonderful musicality but also to thank him for the hundreds of thousands of children he helped," she said.

She said Michael was determined that no one outside the charity should know "how much he gave to the nation's most vulnerable children."

Jane Barron from the Terrence Higgins Trust said Michael made many donations and gifts, including the royalties of his "Don't Let the Sun Go Down on Me" duet with Elton John in 1991.

Michael had spoken publicly about the pain of losing a partner to AIDS early in the epidemic, but he kept his long history of donations to the Trust private.

Rights activist Peter Tatchell, who knew Michael before he achieved fame, said Michael had hidden his homosexuality in the early part of his career because gay public figures were subjected to vicious treatment by the British tabloid press.

He praised the singer for making his sexual orientation known after he was arrested in 1998 for lewd behavior in a public toilet in Los Angeles.

Tatchell said Michael's response to his arrest amounted to "a defiant defense of the right to be gay" that had an impact throughout the gay community.