Tory former minister Lord Roberts of Conwy has died, aged 83, the Conservative Party has said.
Welsh Secretary David Jones said the peer, who as Wyn Roberts served in the Thatcher and Major governments, was "arguably the greatest Welshman of his generation".
Lord Roberts was MP for Conwy from 1970 until 1997 when he was made a life peer and is credited with taking legislation promoting the Welsh language through Parliament.
Mr Jones wrote on Twitter: "So sad to learn of the death of my friend and mentor, Wyn Roberts, a very great Welshman.
"Wyn Roberts was arguably the greatest Welshman of his generation; a wise man and a kind and good friend."
David Cameron also paid tribute, calling Lord Roberts a "great Conservative". Writing on Twitter the Prime Minister said: "I'm sad to hear a great Conservative, Lord Roberts of Conwy, has died. He did so much for Wales, including piloting the Welsh Language Act."
Huw Jones, chairman of the S4C Authority, said former journalist Lord Roberts was a "guardian angel" for the Welsh language broadcaster.
He said: "Wyn Roberts was a guardian angel for the Welsh language and for S4C within the Conservative government of the 80s and 90s.
"Both were close to his heart and he did everything he could to promote and support them. His close interest continued when he became a member of the House of Lords and his wise counsel was priceless.
"Alongside his measured and careful style, he had humour and mischief in his eye and great personal warmth. He made a huge contribution at a critical time for the Welsh language and he will be greatly missed."