Around 1,000 people flocked to St John the Baptist Cathedral in Norwich to celebrate the 40th anniversary of the Catholic Diocese of East Anglia.
The preacher was Cardinal Vincent Nichols, Archbishop of Westminster.
Cardinal Nichols said: 'The cathedral houses the images of three East Anglian saints of the first millennium: St Felix, St Etheldreda and St Edmund: a bishop, an abbess and a king. They remind us that faith in these parts is as old as the hills.
'And they offer us a challenge to be diligent in our mission to live out the faith, playing our part in the continuing story of Christianity in East Anglia now and into the future.'
The Solemn Diocesan Mass was presided over by the bishop of East Anglia, the Rt Rev Alan Hopes, who praised the contribution the diocese had made to life in East Anglia.
He said: 'Over the past 40 years, the diocese has made its mark in the life of the whole Christian community, in its involvement with and outreach to the neediest and most vulnerable in our society.
'The Catholic community has played its full part in working together and co-operating with other Christians, especially in seeking the common good of all.'
Other guests included Antonio Mennini, the Papal Nuncio, the Pope's representative in Britain, and the Archbishop of Southwark, who is a former bishop of East Anglia. They were joined by six other bishops, as well as local civic and religious leaders representing each area of the diocese, which covers Norfolk, Suffolk, Cambridgshire and Peterborough.
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