The Archbishop of Canterbury has said the Church of England still has a "long way to go" as he spoke of the scars and "hurt" suffered by campaigners in favour of women's ordination in the face of "knee-jerk" resistance to change.
The Most Rev Justin Welby was speaking on the 20th anniversary of the first women ordained into the church's priesthood and ahead of the church's expected approval of new rules to allow for women bishops, with the first of these to be ordained early next year.
In a sermon at a national service in St Paul's Cathedral to mark the anniversary, the Archbishop warned against "triumphalism" but said the ordination of women should be celebrated with a "fullness of heart and no holding back".
He said the Church of England may be making progess, but it still had a "long way to go".
"We are not there yet," he told the congregation, which included more than 600 women ordained as priests in the first wave of female ordinations in 1994.
"As we celebrate how far we have come, let us be mindful of the distance yet to travel.
"In 20 years we have come a long way - how did we not see that women and men are equally icons, witnesses, vessels of Christ for the world?"
The Archbishop added that those at the service should not forget the "costly grind" paving the way for the first ordinations of women.
"In our celebrations let us not overlook the cost, the bitterness of disappointment and rejection, the knee-jerk resistance of an institution facing change," he said.
He added: "As a representative of that institution, I want to thank those here today whose costly loyalty, whose scars, make this celebration possible, and to say personally how I grieve that it cost so much, to apologise for my own part in that hurt."
The service was presided over by the Rev Canon Philippa Boardman, canon treasurer of St Paul's, with Archbishop Welby choosing to act as a deacon.
The Church of England backed the ordination of women to the priesthood in 1992 and women were ordained from March 1994.
The number of ordained women in the Church of England has now risen to around a third - 3,827 out of 12, 814 - and women work in a range of posts from full-time parish priests to chaplaincies in hospitals, prisons, schools and universities.
The service comes before the Church of England is expected to give final approval to legislation introducing women bishops in July, paving the way for the first female bishop to be appointed by early next year.
Earlier on Saturday, hundreds of women clergy and their family and friends have gathered at a celebratory picnic at Church House in Westminster in central London spoke of their joy at being able to celebrate 20 years since the first women were consecrated into the priesthood in 1994.
The Rev Rose Hudson-Wilkin, Speaker's Chaplain to the House of Commons, held a placard at the event bearing the words "Women: Beautifully, wonderfully made in the image of God!" - first used on the steps of Church House when the Church of England voted in favour of female ordination in 1992.
"This was used back in 1992 when we had the vote. I stood on the steps of Church House silently because we were told we should not celebrate in case we upset others," she said.
"Today we are going to celebrate."
The Rev Christine Bolhill, who was ordained in 1994, said: "When we were ordained as priests we were told not to celebrate. The Church has never really had a national celebration of having women as priests. Finally after 20 years, the Church of England is celebrating that women are priests."
The Rev Christine Wheeler, 59, who was eight months pregnant when she was ordained in St Paul's Cathedral in April 1994, said attitudes had changed since the first ordinations.
"I was eight months pregnant when I was ordained. There were people who would not take the chalice from a woman. I was an (altar) server at the age of 16 years old and even then there were people who tut-tutted about that.
"There were people who would not take communion from a woman even if she was consecrated. A lot has changed."
Former NHS radiographer the Rev Christine Pollard, from Coventry, was a deacon for four years before being ordained at Coventry Cathedral in April 1994. She said she had been "perfectly happy" as a radiographer until she felt "God rattling my cage."
Commenting on the situation before the Church backed the ordination of women, she said: "It was quite bizarre, I felt God calling me to do something that the law said I could not do."