The SSPX was founded in 1970 in opposition to the modernising reforms made by the Roman Catholic Church in the 1960s, at what was known as the Second Vatican Council. The Society is thought to number around 600,000 worshippers globally.

In response to the Vatican’s decree, Rita Reid, an SSPX worshipper from Jersey in the Channel Islands, said: “It actually makes me feel quite strong.

“Before the consecrations yesterday I said to my husband, ‘Do you know what? Even if they excommunicate us, go ahead, bring it on, it’s not going to make one bit of difference.'”

The Society rejects changes made to how Mass is celebrated – for example it still holds its services in Latin rather than everyday language, and priests face the altar rather than the congregation.

In SSPX Masses the communion bread has to be given straight into the mouths of kneeling worshippers by the priest, as opposed to churchgoers being able to stand and hold it themselves.

Women in the group also tend to cover their heads for services and followers of SSPX tend to be more socially conservative in general.

The SSPX also opposes the modern Catholic Church’s stance on more dialogue with other Christian denominations and other faiths.

For Rita, 76, SSPX ceremonies are much more “profound”, where she feels “the true presence of Jesus”.

She says there is no comparison with the standard Catholic Mass, which she describes as “so weak and wishy-washy”.

The retired B&B owner used to attend modern Catholic services as well as SSPX ones, but complained that in the standard Mass traditional social values – like no sex before marriage – was no longer taught.

“I think a lot of young people now that go to novus ordo [the standard liturgy] think ‘oh well, it’s all right, we can do these things’.”

The Society’s main presence is in the US and France but it holds Masses at 26 locations around the UK, from Lerwick in Shetland down to Devon, with its main centre being in Wimbledon, South London.

At one point in the 1980s, bishops from the Society were excommunicated for disobeying Rome, but that decision was later reversed.

More recently, efforts had been made to reconcile with the SSPX, but the Vatican’s response to this week’s events was more aggressive than before, and more severe than predicted.

It was widely expected that Wednesday’s event in Geneva would lead to excommunication of the bishops involved.

But the excommunication of all those lay people who continue to be a part of SSPX was a surprise to many, with the traditionalist group now as far from the centre of power of the Roman Catholic Church as it has ever been.

Excommunication is one of the harshest punishments that can be given by the Church, effectively expelling the offender from the religion and excluding them from Catholic life.

It means a baptised follower is “out of communion” with the Church – meaning they cannot receive the sacraments, for example going to confession, or get married within the Roman Catholic Church.

The Vatican said on Thursday: “The sacred ministers of the Society of St Pius X administer the sacraments illicitly, while the sacrament of penance they administer and the marriages they witness are invalid.”

It means SSPX members now have to choose whether to stay part of a group that is in “schism”, or leave behind the things they believe are right in order to stay part of the Catholic Church.

However it is clear that many SSPX members believe it is the Vatican that has moved away from true doctrine, not them.