The service was attended by a raft of leading figures from Welsh public life and sport.
First Minister Rhodri Morgan, who was among those at the service, has described him as "one of the outstanding Welshmen of the 20th Century".
Sir Tasker was WRU President for 11 years, and the national team wore black armbands in tribute to him for their opening game in the Rugby World Cup. At the age of 25, he was awarded the Victoria Cross, Britain's highest honour for gallantry, for an assault on a German machine-gun post in northern France.
After the war ended he took up law as a career and rose through the legal system to become deputy lord chief justice.
He acted as deputy to the attorney-general in the tribunal into the 1966 Aberfan disaster when a coal tip slid onto the South Wales valleys village, killing 144 people, 116 of them children.