The Roman Catholic Church has decided to use beer mats and posters as part of a campaign to recruit more priests.
Cardinal Murphy-O'Connor says the church may have to change
Cardinal Cormac Murphy-O'Connor will highlight the problem in his Westminster diocese in a letter to be read to church congregations.
The cardinal will tell people that the sharp decline in the number of priests means that church-goers must play a bigger part in running their parishes.
He will also say many parishes may have to cope without a resident priest.
Cardinal Murphy-O'Connor will make the plea in Westminster on Sunday, as part of ambitious plans to reform the diocese.
If the changes are made in Westminster, the seat of the Roman Catholic Church in England and Wales, it could spark similar changes in parishes all over Britain.
The church is launching a recruitment campaign that will use beermats in pubs and posters on the London Underground to promote the priesthood.
Beermats and posters
The number of priests working at Westminster has fallen from 850 in 1990 to 600 this year. The number is expected to decline to 470 over the next decade.
Under new proposals, lay ministers may be allowed to live in clergy houses in areas where priests are not present, and be able to run weekday services.
Some responses to a consultation said priests should be allowed to marry, but Cardinal Murphy O'Connor said the Roman Catholic Church as a whole would have to change such a policy.
Catholic priest Father Ray Lyons told the BBC News website: "Involvement of the laity is a right and responsibility because of their baptism, regardless of the decline of priests.
"Ninety-nine percent of the church is the laity, they pay for everything."
Fr Lyons said there had been a doubling in numbers of Roman Catholic priests in the UK between 1945 and 1977, and numbers were falling to the level they had been at in 1940.
"We still have the third or fourth best ratio of Catholic priests to Catholic population in the world," he said.
There was a priest for every 850 Catholics in the UK, compared to one for every 20,000 in Brazil, he added.