"Welsh rugby has lost a great friend. For almost forty years he lit up the lives of Welsh people around the world with his fantastic grip on Welsh life and humour. Who can ever forget the village of Aberflyarff, located in Scrumcap Valley on the River Efflew, the barmaid Bromide Lil and back row man Attila Groinstomper," said WRU Group Chief Executive Roger Lewis.
"He helped to immortalise the great Welsh players of the seventies with his portrayals of them and his work in rugby never failed to raise a smile. His range of work was not merely confined to the sporting arena and his political cartoons displayed a sharp cutting edge and no little humour.
"He seemed to be at one with what was going on in Wales and was an integral part of the nation's culture over the past forty years. He will be greatly missed and our sympathies go to his sons Darryl and Chris."
Gren had been ill for some time and passed away in hospital on Wednesday January 3rd, with his two sons at his bedside. Four times the Provincial Cartoonist of the Year, he was awarded the MBE in the New Year's Honours list in 1989.
He often described himself as the official 'war artist' of the WRU and wrote and illustrated the 'Duffers Guide to Rugby' and 'Ponty an' Pop: The Royal Aberflyarff Story'. His calendars were immensely popular, as were his billboard sheep, Neville and Nigel.
A few seasons ago Gren completed a series of three cartoons for the programmes for the Welsh home games in the RBS Six Nations Championship.