David Green, 74, passed away after a battle with lung cancer and he left behind no money or family to pay for a memorial service.

The Masters of Sex star met Green while working on his documentary Valley's Rebellion, about political disillusionment in Wales, and Sheen is now urging fans to make donations to a crowdfunding drive to cover the veteran activist's funeral costs.

In a post on his Twitter.com page, he writes, "I met Dave Green making my documentary. He was a member of the United Valleys Action Group. It gave him a platform - he made full use of it. He made a big impact on me... He was what's known as a character. Dave died last week of lung cancer. He was 74. He had no family and no money. I've been told he faces a pauper's funeral. It's my honour to help. If anyone else would like to, you can do so."