A special service is being held today in St Paul's Cathedral, celebrating two decades of female ordination in the Church of England.

At 2.00pm there will be a welcome and address at Westminster Abbey, followed by a walk of witness to St Paul's Cathedral, where the service will start at 5.00pm.

The Archbishop of Canterbury will be preaching to representatives of all 42 dioceses of the Church of England, and every woman who was ordained in 1994 has been invited to take part, sharing Bible readings and their reflections on their ordination.

There will also be an address from the former Bishop of Bristol, Barry Rogerson, who was the first bishop to ordain women.

The Very Reverend June Osborne, a 1994 ordinand who is now the first female Dean of Salisbury Cathedral, shared her view of that historic year: "Like all special days in your life the memory of my own ordination at St Paul's Cathedral is still vivid. I feel immensely privileged to have seen history changed in those months of welcoming women into the ministry of the Church.

"This is the season for celebration and thanksgiving because opening the ordained ministry to women has been the true and right thing to do.

"Both women and men have spiritual skills and gifts to offer. Both women and men are charged with making the world a better place and defending the poor. Women as well as men make good clergy who serve their communities and pray for their people."

The Reverend Canon Philippa Boardman, Treasurer of St Paul's who was also a 1994 ordinand, said: "Twenty years ago when the huge wooden doors of St Paul's Cathedral swung open as the procession of the soon-to-be-ordained women came in, it was a time of great hope and also some concern about the impact on the unity of the Church.

"Twenty years on, many of these hopes have been fulfilled and fears allayed as women and men have worked together as priests, bringing new life to churches and parishes including some of the neediest communities in our country.

"In the great history of the Church, twenty years is no time at all, and I am conscious that this is just the beginning of so many good things to come."

Vicky Beeching, theologian and religious commentator, welcomed the celebration: "I'm delighted the Church is making such a public statement to endorse and thank all the women in ordained ministry.

"The procession through the streets of London shows an unashamed, public sign that ordained women are valued by the Church and that their contributions over the past 20 years are being celebrated."

Praising the Church's progress, Ms Beeching said: "The high number of female priests in the C of E is really encouraging, despite it only having been possible for the past 20 years. On that basis, other sectors - like politics or the academic world - are somewhat put to shame in their much longer-standing gender imbalances."

But in Ms Beeching's view, the service is tinged with the knowledge that women still cannot join the higher ranks of bishop and archbishop, describing it as an "elephant in the room".

"That's the odd tension - a huge service to celebrate women yet doing so in the reality that women are still only affirmed to a certain degree. I look forward to a future service where women are celebrated without any stained-glass ceilings or limitations."

Susie Leafe, the director of the evangelical Anglican group Reform, was critical of the service, saying: "What exactly are we celebrating? Women have been ministering in the church for 2.000 years, not 20.

"[Women] serve the sick, the elderly, the housebound; they teach the bible in numerous settings; they run drop-in centres, youth groups, Sunday schools; foodbanks; they act as church wardens, they ensure the roof stays on and the door stays open. Apparently their contribution is not worth celebrating.

"The very fact that this event is taking place begs some serious questions about how some people view ministry in the Church of England."

Music will be provided by Salisbury Cathedral Girl Choristers alongside the St Paul's Cathedral Consort.

The public cannot attend inside the Cathedral, but there will be a big screen display in Paternoster Square.