Scottish actor Alan Cumming said on Friday he had returned a UK state honour in protest at the "toxicity" of the British Empire, 14 years after receiving the award.

Cumming, who is largely US-based, was made an officer of the Order of the British Empire (OBE) in 2009 in recognition of his acting and his work for LGBTQ+ rights in the United States.

But he said he had reflected further on the role of the monarchy after the death last year of Queen Elizabeth II.

That refection, "and especially the way the British Empire profited at the expense (and death) of indigenous peoples across the world really opened my eyes", Cumming said in an Instagram post marking his 58th birthday.

Gay rights had advanced meanwhile in the United States, and any benefit from the award was "now less potent than the misgivings I have being associated with the toxicity of empire", Cumming said.

"So, I returned my award, explained my reasons and reiterated my great gratitude for being given it in the first place. I'm now back to being plain old Alan Cumming again. Happy birthday to me!"

The queen's death also forced a reckoning for Welsh actor Michael Sheen, who handed back his OBE late last year and urged an end to the heir to the British crown being named prince of Wales.

Further back, Beatles songwriter John Lennon returned his MBE medal -- which ranks below an OBE -- in 1969 in protest at UK involvement in a Nigerian civil war and its support for the US war in Vietnam.