By Robert Pigott
BBC religious affairs correspondent
St Therese's remains spent a few hours in Wormwood Scrubs prison
In life, St Therese of Lisieux was virtually unknown - a Carmelite nun by the age of 15 and dead from tuberculosis in 1897 at only 24.
But in death she became one of the Church's brightest stars.
To judge from the thousands of Roman Catholics who have queued to see bones from her thigh and foot on their month-long visit to England and Wales, her star quality endures to this day.
Two thousand people an hour are expected to file past the ornate jacaranda wood casket in Westminster Cathedral to view the bones through a glass window, before they return via the Channel Tunnel to France.
Therese's popularity resulted from a posthumous autobiography that revealed her struggles with doubt.
The Provost of Birmingham Oratory, Father Paul Chavasse, says those doubts strike a powerful chord in a rationalist and sceptical age.
"She had long, long, periods when she didn't so much feel the presence of God as the absence of God", he said.
'Don't feel worthy'
has a specific message for an age, which, in so many ways, is searching for meaning and for a spiritual understanding of what is going on."
But there is another characteristic of saints that explains Therese's special appeal - their role in Roman Catholic belief as intermediaries between the faithful and God.
Grace is a Roman Catholic who travelled from Cambridge to see the relics arrive at Wormwood Scrubs jail in west London.
She watched as the decorated casket - clearly visible through the open door of a people carrier - entered the forbidding Victorian gatehouse at the high-security jail.
Grace said Therese's simplicity and humility made her all the more approachable as a "friend in heaven".
She explained: "We feel we can't pray directly to God but we use the saints as intermediaries on our behalf to ask our favours. That's why we pray a lot to saints.
"It's using them to speak to God on our behalf because we don't feel worthy enough to speak to him directly."
Inside the jail, 100 prisoners in regulation grey flannel tracksuits, many wearing rosaries, knelt and prayed before the casket in the prison chapel as others dispensed incense.
In a couple of weeks, Roman Catholics will celebrate All Saints' Day, with masses and soaring music.
It will be a celebration of Christians, such as Therese, who the Church believes are in heaven.
Catholics invest great faith in the power of prayers directed through such saints, and they insist that proximity to their earthly remains intensifies the sense of connection with God.
But it is a practice fiercely resisted by some Protestant Christians.
The Rev Peter Ratcliff, editor of the traditionalist Protestant journal The English Churchman, denounced the practice of praying to saints as superstition.
He said: "The Roman Catholic Church obscures - whether it be through indulgences, relics, the Mass, priests, penances and all sorts of things - it obscures the Lord Jesus Christ. There's no reason at all that anyone should be able to pray to anyone who's dead."
Roman Catholics believe that the relics provide a way of getting closer to God
Relics of St Therese were taken to Baghdad in 2002 in an effort to forestall the Iraq war, and some have even been released into orbit around the Earth.
But Church leaders insist there's nothing magical or mystical about the relics. They are just a focus for prayer.
The Archbishop of Westminster, the Most Reverend Vincent Nichols - who will send the relics on their journey back to France - rejected the suggestion that the relics' journey was at odds with a secular age.
He said: "It might be out of step with that element of secularism and scepticism, but that's not the whole of society.
'Things of God'
"I think there is still a real hunger in our society for the things of God. I think that what this pilgrimage of the relics shows is that we misunderstand ourselves if we rule out the spiritual element of every human being and every human life", he said.
"If we push that to the margins we are depriving ourselves, and society, of a great source of generosity and heroism and love."
St Therese's popularity might reveal a hunger for "the things of God", but it also suggests widespread interest in her particular approach to the divine.
When Therese was a young nun, the image of God presented by the Church was designed to inspire awe and even fear.
But she described a personal relationship, even a friendship with God and that still seems to strike a chord today.